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Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2017
Document And Entity Information [Abstract]
Document Type	S-1/A
Amendment Flag	true
Amendment Description	Amendment No. 2 to Form S-1
Document Period End Date	Sep. 30, 2017
Trading Symbol	TNDM
Entity Registrant Name	TANDEM DIABETES CARE INC
Entity Central Index Key	0001438133
Entity Filer Category	Smaller Reporting Company

CONDENSED BALANCE SHEETS - USD ($)
$ in Thousands

Sep. 30, 2017

Dec. 31, 2016

Dec. 31, 2015

Current assets:

Cash and cash equivalents

$ 12,079

$ 44,678

$ 43,088

Restricted cash

2,000

Short-term investments

459

8,860

28,018

Accounts receivable, net

10,582

11,172

14,055

Inventory, net

29,985

21,195

17,543

Prepaid and other current assets

2,887

4,187

2,280

Total current assets

55,992

92,092

106,984

Restricted cash-long-term

10,000

Property and equipment, net

20,286

18,409

15,526

Other long-term assets

160

107

105

Total assets

87,977

112,392

124,725

Current liabilities:

Accounts payable

7,605

7,513

5,234

Accrued expense

2,536

1,629

2,121

Employee-related liabilities

11,413

10,183

11,761

Deferred revenue

2,295

5,208

1,822

Other current liabilities

5,562

6,943

5,582

Total current liabilities

29,411

31,476

26,520

Notes payable-long-term

75,596

78,960

29,275

Deferred rent-long-term

4,142

2,609

2,743

Other long-term liabilities

6,786

5,274

2,719

Total liabilities

115,935

118,319

61,257

Commitments and contingencies

Stockholders' equity (deficit):

Common stock

^[1]

Additional paid-in capital

438,244

398,651

384,578

Accumulated other comprehensive income (loss)

(1)

Accumulated deficit

(466,207)

(404,580)

(321,133)

Total stockholders' equity (deficit)

(27,958)

(5,927)

63,468

Total liabilities and stockholders' deficit

87,977

112,392

124,725

Patents [Member]

Current assets:

Patents, net

$ 1,539

$ 1,784

$ 2,110

[1]	The issued and outstanding shares of common stock have been restated for all periods presented to reflect the effects of the 1-for-10 reverse stock split, which was effective on October 9, 2017 as described in Note 7.

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000	100,000,000
Common stock, shares issued	5,487,000	3,110,000	3,026,000
Common stock, shares outstanding	5,487,000	3,110,000	3,026,000

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)
shares in Thousands, $ in Thousands

9 Months Ended

12 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2014

Income Statement [Abstract]

Sales

$ 67,306

$ 55,336

$ 84,248

$ 72,850

$ 49,722

Cost of sales

40,680

41,809

60,656

46,270

34,474

Gross profit (loss)

26,626

13,527

23,592

26,580

15,248

Operating expenses:

Selling, general and administrative

65,077

63,768

82,834

78,621

75,121

Research and development

14,910

14,464

18,809

16,963

15,791

Total operating expenses

79,987

78,232

101,643

95,584

90,912

Operating loss

(53,361)

(64,705)

(78,051)

(69,004)

(75,664)

Other income (expense), net

Interest and other income

179

258

296

337

112

Interest and other expense

(8,445)

(4,177)

(5,707)

(3,741)

(3,901)

Total other expense, net

(8,266)

(3,919)

(5,411)

(3,404)

(3,789)

Loss before taxes

(83,462)

(72,408)

(79,453)

Provision for income tax (benefit) expense

(15)

Net loss

(61,627)

(68,624)

(83,447)

(72,418)

(79,524)

Other comprehensive loss:

Unrealized gain (loss) on short-term investments

(23)

(21)

Comprehensive loss

$ (61,626)

$ (68,647)

$ (83,468)

$ (72,406)

$ (79,516)

Net loss per share, basic and diluted

$ (13.79)

^[1]

$ (22.52)

^[1]

$ (27.30)

$ (25.04)

$ (34.17)

Weighted average shares used to compute basic and diluted net loss per share

4,468

^[1]

3,047

^[1]

3,057

2,892

2,327

[1]	The issued and outstanding shares of common stock have been restated for all periods presented to reflect the effects of the 1-for-10 reverse stock split, which was effective on October 9, 2017 as described in Note 7.

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Parenthetical) - Subsequent Event [Member]	Oct. 09, 2017
Reverse stock split description	1-for-10 reverse stock split
Reverse stock split, conversion ratio	0.1

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (61,627)	$ (68,624)	$ (83,447)	$ (72,418)	$ (79,524)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	4,737	4,017	5,489	4,829	4,389
Interest expense related to amortization of debt discount and debt issuance costs	1,338	194	274	138	219
Payment in kind interest accrual of notes payable	1,236	675	927	153
Provision for allowance for doubtful accounts	664	666	632	70	188
Provision for inventory reserve	316	1,805	3,343	404	163
Amortization of (discount) premium on short-term investments	(16)	(59)	(85)	4	(53)
Stock-based compensation expense	10,502	8,733	11,660	13,096	14,995
Other	69	(37)	(78)	(76)	41
Changes in operating assets and liabilities:
Accounts receivable, net	(73)	5,191	2,251	(6,473)	(2,541)
Inventory, net	(9,038)	(7,110)	(6,904)	(6,084)	(1,820)
Prepaid and other current assets	1,133	(1,408)	(2,466)	(395)	(82)
Other long-term assets	(53)	(8)	(2)	131	(150)
Accounts payable	522	291	3,234	3,355	(1,225)
Accrued expenses	907	(144)	(497)	(734)	973
Employee-related liabilities	797	(1,225)	(1,578)	2,039	3,846
Deferred revenue	(4,137)	8,528	4,610	981	429
Other current liabilities	(601)	1,348	573	1,924	(1,575)
Deferred rent	(425)	(566)	1	(631)	(461)
Other long-term liabilities	(746)	142	890	923	810
Net cash used in operating activities	(54,495)	(47,591)	(61,173)	(58,764)	(61,378)
Investing activities
Purchase of short-term investments		(25,890)	(30,622)	(80,191)	(67,101)
Proceeds from sales and maturities of short-term investments	8,500	37,950	50,000	88,450	36,210
Purchase of property and equipment	(4,299)	(6,187)	(8,930)	(5,764)	(4,406)
Purchase of patents				(74)	(173)
Net cash provided by (used in) investing activities	4,201	5,873	10,448	2,421	(35,470)
Financing activities
Issuance of notes payable, net of issuance costs		14,994	49,994		29,925
Restricted cash in connection with notes payable	(8,000)				50
Principal payments on notes payable					(30,000)
Proceeds from public offering, net of offering costs	25,125			64,862
Proceeds from issuance of common stock	570	1,592	2,321	3,393	3,664
Net cash provided by financing activities	17,695	16,586	52,315	68,255	3,639
Net increase (decrease) in cash and cash equivalents	(32,599)	(25,132)	1,590	11,912	(93,209)
Cash and cash equivalents at beginning of period	44,678	43,088	43,088	31,176	124,385
Cash and cash equivalents at end of period	12,079	17,956	44,678	43,088	31,176
Supplemental disclosures of cash flow information
Interest paid	5,871	3,205	4,401	3,345	3,369
Income taxes paid			23	9	71
Supplemental schedule of noncash investing and financing activities
Lease incentive - lessor-paid tenant improvements	3,037			933	1,604
Property and equipment included in accounts payable & other current liabilities			$ 501	$ 1,457	789
Debt discount included in other long-term liabilities	4,116	454
Patent included in accrued expense					$ 74
Common stock warrants issued in connection with term loan	3,331
Property and equipment included in accounts payable	$ 72	$ 802

STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2013	$ 115,537	$ 2	$ 284,726		$ (169,191)
Balance, Shares at Dec. 31, 2013		2,293,000
Exercise of common stock warrants	138		138
Exercise of common stock warrants, Shares		33,000
Exercise of stock options	325		325
Exercise of stock options, Shares		14,000
Issuance of common stock for Employee Stock Purchase Plan	3,168		3,168
Issuance of common stock for Employee Stock Purchase Plan, Shares		25,000
Stock-based compensation	14,920		14,920
Unrealized gain (loss) on short-term investments	8			$ 8
Net loss	(79,524)				(79,524)
Balance at Dec. 31, 2014	54,572	$ 2	303,277	8	(248,715)
Balance, Shares at Dec. 31, 2014		2,366,000
Exercise of common stock warrants	122		122
Exercise of common stock warrants, Shares		2,000
Exercise of stock options	$ 337		337
Exercise of stock options, Shares	24,355	24,000
Issuance of common stock in public offering, net of underwriter's discount and offering costs	$ 64,862	$ 1	64,861
Issuance of common stock in public offering, net of underwriter's discount and offering costs, Shares		604,000
Issuance of common stock for Employee Stock Purchase Plan	2,934		2,934
Issuance of common stock for Employee Stock Purchase Plan, Shares		31,000
Stock-based compensation	13,047		13,047
Unrealized gain (loss) on short-term investments	12			12
Net loss	(72,418)				(72,418)
Balance at Dec. 31, 2015	63,468	$ 3	384,578	20	(321,133)
Balance, Shares at Dec. 31, 2015		3,026,000
Exercise of stock options	$ 170		170
Exercise of stock options, Shares	14,897	15,000
Issuance of common stock for Employee Stock Purchase Plan	$ 2,151		2,151
Issuance of common stock for Employee Stock Purchase Plan, Shares		69,000
Stock-based compensation	11,752		11,752
Unrealized gain (loss) on short-term investments	(21)			(21)
Net loss	(83,447)				(83,447)
Balance at Dec. 31, 2016	$ (5,927)	$ 3	$ 398,651	$ (1)	$ (404,580)
Balance, Shares at Dec. 31, 2016		3,110,000
Exercise of stock options, Shares	24,408
Unrealized gain (loss) on short-term investments	$ 1
Net loss	(61,627)
Balance at Sep. 30, 2017	$ (27,958)

Organization and Basis of Presentation

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Basis of Presentation

1. Organization and Basis of Presentation

The Company

Tandem Diabetes Care, Inc. is a medical device company focused on the design, development and commercialization of products for people with insulin-dependent diabetes. The Company is incorporated in the state of Delaware. Unless the context requires otherwise, the terms the “Company” or “Tandem” refer to Tandem Diabetes Care, Inc.

The Company manufactures and sells insulin pump products in the United States that are designed to address large and differentiated needs of the insulin-dependent diabetes market. The Company’s pump products currently include:

•

the t:slim X2 Insulin Delivery System, or t:slim X2, the next-generation flagship product that is updatable and designed to display Dexcom G5 continuous glucose monitoring, or CGM, sensor information directly on the pump Home Screen; and

•

the t:flex Insulin Delivery System, or t:flex, for people with greater insulin needs.

The Company began commercial sales of its first product, t:slim, in August 2012. During 2015, the Company commenced commercial sales of two additional insulin pumps: t:flex in May 2015 and t:slim G4 in September 2015. In October 2016, the Company commenced commercial sales of t:slim X2 and discontinued new sales of t:slim. In August 2017, the Company commenced commercial sales of t:slim X2 with Dexcom G5 Mobile CGM integration, or t:slim X2 with G5, and discontinued new sales of t:slim G4. The Company will continue to provide ongoing service and support to existing t:slim and t:slim G4 customers.

In July 2016, the Company received clearance from the U.S. Food and Drug Administration (“FDA”) to begin offering the Tandem Device Updater, a Mac and PC-compatible tool for the remote update of Tandem insulin pump software.

In July 2016, the Company also announced and launched a Technology Upgrade Program that provided eligible t:slim and t:slim G4 customers a path to obtain t:slim X2, or, as of August 2017, t:slim X2 with G5. Participating customers had the right to exchange their original t:slim and t:slim G4 for a t:slim X2 or t:slim X2 with G5, under a variable pricing structure. The Technology Upgrade Program expired on September 30, 2017.

In September 2017, the Company commenced commercial sales of products using the t:lock^TM Connector, or t:lock, which replaces the standard Luer-lok connector that historically joined an infusion set to the cartridge. t:lock incorporates a smaller inner cavity than the Luer-lok connector, which reduces the amount of insulin used in the process and reduces the time required to fill the infusion set tubing.

Effective December 31, 2016, the Company adopted FASB Accounting Standard Codification (“ASC”) Topic 205-40, Presentation of Financial Statements—Going Concern, which requires management to evaluate whether there are relevant conditions and events that, in the aggregate, raise substantial doubt about the entity’s ability to continue as a going concern and to meet its obligations as they become due within one year after the date the financial statements are issued.

The Company has incurred operating losses since its inception and, as reflected in the accompanying financial statements, the Company has an accumulated deficit of $466.2 million as of September 30, 2017, which reflects a net loss of $61.6 million for the nine months ended September 30, 2017. The Company had cash and cash equivalents and short-term investments of $22.5 million at September 30, 2017, including $10.0 million of restricted cash as required by the Company’s term loan agreement (as amended, the “Term Loan Agreement”) with Capital Royalty Partners II, L.P. and its affiliate funds (“Capital Royalty Partners”). The Company used $54.5 million in cash from operations in the nine months ended September 30, 2017. The Company concluded that, at the date the financial statements were issued, it did not have sufficient cash to fund its operations for the next twelve months without additional financing and, therefore, there was substantial doubt about its ability to continue as a going concern within one year after the date the financial statements were issued.

On October 9, 2017, the Company effected a 1-for-10 reverse stock split of its issued and outstanding shares of common stock. The par value per share and the authorized number of shares of common stock and preferred stock were not adjusted as a result of the reverse stock split. All common stock share and per-share amounts for all periods presented in these condensed financial statements have been adjusted to reflect the reverse stock split. The number of authorized shares of common stock remains at 100 million shares.

The Company completed a registered public offering on October 17, 2017, or the October Financing, which resulted in gross proceeds to the Company of $16.2 million, before deducting underwriting discounts and commissions and other offering expenses (see Note 9 “Subsequent Event”). As part of the October Financing, the Company issued 4,630,000 shares of common stock, Series A warrants to purchase 4,630,000 shares of common stock and Series B warrants to purchase 4,630,000 shares of common stock, at a public offering price of $3.50 per share and accompanying warrants. The Series A warrants have an exercise price of $3.50 per share, are immediately exercisable, and will expire on the 5-year anniversary of the date of issuance. The Series B warrants have an exercise price of $3.50 per share, are immediately exercisable, and will expire on the 6-month anniversary of the date of issuance. Each series of warrants, if exercised by all holders in full, may result in additional gross proceeds of $16.2 million to the Company. As a result of the completion of the financing, the Company has satisfied the equity financing covenant in the Term Loan Agreement (see Note 6, “Term Loan Agreement”), although it remains subject to additional covenants.

The Company believes it will be necessary to raise additional funding. The Company intends to seek additional capital from public or private offerings of its capital stock or it may elect to borrow additional amounts under new debt financing arrangements or from other sources. If the Company issues equity or convertible debt securities to raise additional funding, its existing stockholders may experience dilution, it may incur significant financing costs, and the new equity or convertible debt securities may have rights, preferences and privileges senior to those of its existing stockholders. If the Company issues debt securities to raise additional funding, it would incur additional debt service obligations, it could become subject to additional restrictions limiting its ability to operate its business, and it may be required to further encumber its assets. The Company’s ability to continue as a going concern, meet its minimum liquidity requirements, satisfy the covenants under the Term Loan Agreement, and execute its business strategy is dependent on its ability to raise significant additional capital, of which there can be no assurance. If the Company cannot generate sufficient revenues from the sale of its products or secure additional financing on acceptable terms, it may be forced to significantly alter its business strategy, substantially curtail or modify its current operations, or cease operations altogether.

Basis of Presentation

The Company has prepared the accompanying unaudited condensed financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information. Accordingly, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments which are of a normal and recurring nature, considered necessary for a fair presentation of the financial information contained herein, have been included.

Interim financial results are not necessarily indicative of results anticipated for the full year or any other period(s). These unaudited condensed financial statements should be read in conjunction with the Company’s audited financial statements and accompanying footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 (“Annual Report”), from which the balance sheet information herein was derived. These unaudited condensed financial statements exclude disclosures required by U.S. GAAP for complete financial statements.

1. Organization and Basis of Presentation

The Company

•

the t:slim Insulin Delivery System, or t:slim,

•

the t:flex Insulin Delivery System, or t:flex,

•

the t:slim G4 Insulin Delivery System, or t:slim G4, and

•

the t:slim X2 Insulin Delivery System, or t:slim X2.

In July 2016, the Company announced and launched a Technology Upgrade Program that provides eligible t:slim and t:slim G4 customers a path to obtain t:slim X2. Participating customers have the right to exchange their original t:slim and t:slim G4 for a t:slim X2, under a variable pricing structure. The Technology Upgrade Program expires on September 30, 2017.

In October 2016, the Company began shipping t:slim X2. As a result, the Company discontinued new shipments of t:slim, though the Company will continue to provide ongoing service and support to existing t:slim customers.

For the year ended December 31, 2016, the Company has adopted FASB Accounting Standard Codification ASC Topic 205-40, Presentation of Financial Statements – Going Concern, which requires that management evaluate whether there are relevant conditions and events that, in the aggregate, raise substantial doubt about the entity’s ability to continue as a going concern and to meet its obligations as they become due within one year after the date that the financial statements are issued.

On October 9, 2017, the Company effected a 1-for-10 reverse stock split of its issued and outstanding shares of common stock. The par value per share and the authorized number of shares of common stock and preferred stock were not adjusted as a result of the reverse stock split. All common stock share and per-share amounts for all periods presented in these financial statements have been adjusted to reflect the reverse stock split. The number of authorized shares of common stock remains at 100 million shares.

The Company has incurred operating losses since its inception and, as reflected in the accompanying financial statements, the Company has an accumulated deficit of $404.6 million as of December 31, 2016, which includes a net loss of $83.4 million for the year ended December 31, 2016. Additionally, the Company used $61.2 million in cash for operations in the year ended December 31, 2016, which exceeded cash and cash equivalents and short-term investments of $53.5 million at December 31, 2016. The Company concluded that, at the date its financial statements for the year ended December 31, 2016 were issued, it did not have sufficient cash to fund its operations through December 31, 2017 without additional financing and, therefore, there was substantial doubt about its ability to continue as a going concern within one year after the date the financial statements were issued.

As a result, the audit report contained in the accompanying financial statements includes an explanatory paragraph that describes conditions that raise substantial doubt about the Company’s ability to continue as a going concern. This explanatory paragraph could constitute a potential event of default under the Company’s existing term loan agreement (as amended by Consent and Amendment Agreement, dated June 20, 2014, Omnibus Amendment Agreement No. 2, dated February 23, 2015, Amendment No. 3 to Term Loan Agreement, dated January 8, 2016, and Waiver and Amendment No. 4 to Term Loan Agreement, dated March 7, 2017, the “Term Loan Agreement”) with Capital Royalty Partners II L.P. and its affiliate funds (“Capital Royalty Partners”). Accordingly, on March 7, 2017, the Company entered into an amendment to the terms of the Term Loan Agreement (the “Fourth Amendment”) that included a limited waiver of the potential event of default that could have occurred due to the explanatory paragraph included in the audit report. (See Note 5 “Term Loan Agreement” and Note 12 “Subsequent Event.”)

The financial statements included in this prospectus have been prepared on a basis that assumes that the Company will continue as a going concern, and do not include any adjustments that may result from the outcome of this uncertainty. This basis of accounting contemplates the recovery of the Company’s assets and the satisfaction of the Company’s liabilities and commitments in the normal course of business and does not include any adjustments to reflect the possible future effects of the recoverability and classification of recorded asset amounts or amounts and classification of liabilities that might be necessary should the Company be unable to continue as a going concern.

The Company believes that it will be necessary to raise additional funding in the form of an equity financing from the sale of common stock. The Company may in the future seek additional capital from public or private offerings of its capital stock or it may elect to borrow additional amounts under new credit lines or from other sources. If the Company issues equity or debt securities to raise additional funds, its existing stockholders may experience dilution, it may incur significant financing costs, and the new equity or debt securities may have rights, preferences and privileges senior to those of its existing stockholders. The Company’s ability to continue as a going concern, meet its minimum liquidity requirements in the future or satisfy the other covenants under the Term Loan Agreement is dependent on its ability to raise significant additional capital, of which there can be no assurance. If the Company cannot generate sufficient revenues from the sale of its products or secure additional financing on acceptable terms, it may be forced to significantly alter its business strategy, substantially curtail its current operations, or cease operations altogether.

Basis of Presentation

The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the Company’s realization of assets and satisfaction of liabilities in the normal course of business. The financial statements do not include any adjustments relating to the recoverability and classification of assets and liabilities that might be necessary should the Company be unable to continue as a going concern. The Company’s continuation as a going concern is dependent upon its ability to raise additional equity or refinance its existing debt and ultimately, to attain profitability. There is no assurance that the Company will be successful in raising additional funds or that, if it does raise additional funds, that it will be able to attain profitability or even continue in business.

Summary of Significant Accounting Policies

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

There have been no significant changes in our significant accounting policies during the nine months ended September 30, 2017, as compared with those disclosed in the Annual Report.

Use of Estimates

The preparation of the financial statements in conformity with U.S. GAAP requires management to make informed estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities in the Company’s financial statements and accompanying footnotes as of the date of the financial statements. Actual results could materially differ from those estimates and assumptions.

Restricted Cash

The Company recorded $10.0 million and $2.0 million of restricted cash as of September 30, 2017 and December 31, 2016, respectively, for the minimum cash balance requirement in connection with the Term Loan Agreement (see Note 6, “Term Loan Agreement”).

Accounts Receivable

The Company grants credit to various customers in the normal course of business. The Company maintains an allowance for doubtful accounts for potential credit losses. Provisions are made based on historical experience, assessment of specific risk, specific review of outstanding invoices, and various additional assumptions and estimates that are believed to be reasonable under the circumstances. Uncollectible accounts are written off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a balance is uncollectible.

Fair Value of Financial Instruments

The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable, accrued expenses, and employee-related liabilities are reasonable estimates of their fair values because of the short-term nature of these assets and liabilities. Short-term investments are carried at fair value. Based on the borrowing rates currently available for loans with similar terms, the Company believes that the fair value of its long-term notes payable approximates its carrying value.

Certain trade-in rights offered by the Company pursuant to the Technology Upgrade Program to certain eligible customers, have been determined to be guarantees under applicable accounting guidance. The Company recorded a liability for the estimated fair value of the guarantees at their inception. The Program expired on September 30, 2017, at which time the remaining guarantee liabilities of $1.1 were recognized as sales. For further details regarding these guarantees, see the information included under the heading “Revenue Recognition” within this Note 2, as well as the information in Note 5, “Fair Value Measurements.”

Revenue Recognition

Revenue is generated primarily from sales in the United States of insulin pumps, disposable cartridges and infusion sets to individual customers and third-party distributors that resell the product to insulin-dependent diabetes customers. The Company is paid directly by customers who use the products, distributors and third-party insurance payors.

Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred and title passed, the price is fixed or determinable, and collectability is reasonably assured.

Trade-In Rights

The Company launched a Technology Upgrade Program in 2016, which expired September 30, 2017. The trade-in rights associated with the Program were accounted for as guarantees or rights to return based on specific factors and circumstances, including the period of time the trade-in rights were exercisable, the likelihood that the trade-in rights would be exercised, and the amount of the specified-price trade-in value.

The Company determined that trade-in rights for t:slim G4 Pump customers were generally guarantees. The Company accounted for the guarantees under applicable accounting standards, which require a guarantor to recognize, at the inception of the guarantees, a liability for the estimated fair value of the obligation undertaken in issuing the guarantees. Subsequently, the initial liability recognized for the guarantees was reduced as the Company was released from the risk under the guarantees, which was when the trade-in right was exercised or the right expired. The guarantees were accounted for as an element of a multiple element arrangement. The estimated fair value of the guarantees was based on various economic and customer behavioral assumptions, including the probability that a trade-in right would be exercised, the specified trade-in amount, the expected fair value of the used t:slim G4 Pump at trade-in and the expected sales price of a t:slim X2 Pump. Upon expiration of the Program at September 30, 2017, the remaining guarantee liabilities of $1.1 were recognized as sales compared to $1.2 million recorded as guarantee liabilities in other current liabilities on the accompanying balance sheets, as of September 30, 2017 and December 31, 2016, respectively.

The Company determined that t:slim Pump trade-in rights were in-substance rights to return products. Such rights to return were accounted for pursuant to the right of return accounting guidance. As the Company did not have sufficient history to reasonably estimate returns associated with trade-in rights, all eligible t:slim Pump sales between July 2016 and October 2016, which is when the Company discontinued new shipments of t:slim, were recorded as deferred revenue until the trade-in right was exercised or the right expired. Despite expiration of the Program at September 30, 2017, the Company recorded $0.2 million for upgrades requested but not yet fulfilled compared to $3.2 million as a trade-in rights reserve in deferred revenue on the accompanying balance sheets, as of September 30, 2017 and December 31, 2016, respectively.

Revenue Recognition for Arrangements with Multiple Deliverables

The Company considers the deliverables in its product offering as separate units of accounting and recognizes deliverables as revenue upon delivery only if (i) the deliverable has standalone value and (ii) the arrangement includes a general right of return relative to the delivered item(s) and delivery or performance of the undelivered item(s) is probable and substantially controlled by the Company. The Company allocates consideration to the separate units of accounting, unless the undelivered elements were deemed perfunctory and inconsequential. The amount of the determined guarantee fair value is allocated in full to the guarantee and the remaining allocable consideration is allocated to other separate units of accounting using the relative selling price method, in which allocation of consideration is based on vendor-specific objective evidence (“VSOE”) if available, third-party evidence (“TPE”), or if VSOE and TPE are not available, management’s best estimate of a standalone selling price (“ESP”) for the undelivered elements.

The Company offers a cloud-based data management application, t:connect, which is made available to customers upon purchase of any of its insulin pumps. In July 2016, the Company received clearance from the FDA to begin offering the Tandem Device Updater, a Mac and PC-compatible tool for the remote update of Tandem insulin pump software. Utilizing Tandem Device Updater, the Company may from time to time provide future unspecified software upgrades to the insulin pump’s essential software. The t:connect service and the embedded right included with qualifying insulin pumps to receive, on a when-and-if-available basis, future unspecified software upgrades relating to the product’s essential software are deemed undelivered elements at the time of the insulin pump sale. Because the Company has neither VSOE nor TPE for these deliverables, the allocation of revenue is based on the Company’s ESP. The Company establishes its ESP based on the estimated cost to provide such services, including consideration for a reasonable profit margin, which is then corroborated by comparable market data. The Company allocates fair value based on management’s ESP to these elements at the time of sale and recognizes the revenue over a four-year period, which is the hosting period for t:connect and the period that software upgrades are expected to be provided. At September 30, 2017 and December 31, 2016, $1.8 million and $1.6 million, respectively, were recorded as deferred revenue for these undelivered elements. All other undelivered elements at the time of sale are deemed inconsequential or perfunctory.

Product Returns

The Company offers a 30-day right of return to its customers from the date of shipment of any of its insulin pumps, provided a physician’s confirmation of the medical reason for the return is received. Estimated allowances for sales returns are based on historical returned quantities as compared to pump shipments in those same periods of return. The return rate is then applied to the sales of the current period to establish a reserve at the end of the period. The return rates used in the reserve are adjusted for known or expected changes in the marketplace when appropriate. The allowance for product returns is recorded as a reduction of revenue and accounts receivable in the period in which the related sale is recorded. The amount recorded on the Company’s balance sheets for product return allowance was $0.2 million and $0.2 million at September 30, 2017 and December 31, 2016, respectively. Actual product returns have not differed materially from estimated amounts reserved in the accompanying condensed financial statements.

Warranty Reserve

The Company generally provides a four-year warranty on its insulin pumps to end user customers and may replace any pumps that do not function in accordance with the product specifications. Insulin pumps returned to the Company may be refurbished and redeployed. Additionally, the Company offers a six-month warranty on disposable cartridges and infusion sets. Estimated warranty costs are recorded at the time of shipment. Warranty costs are estimated based on the current expected product replacement cost and expected replacement rates based on historical experience. The Company evaluates the reserve quarterly and makes adjustments when appropriate. Changes to the actual replacement rates or the expected product replacement cost could have a material impact on the Company’s warranty reserve.

At September 30, 2017 and December 31, 2016, the warranty reserve was $4.8 million and $5.7 million, respectively. The following table provides a reconciliation of the change in product warranty liabilities from December 31, 2016 through September 30, 2017 (in thousands):


Balance at December 31, 2016	$	5,690
Provision for warranties issued during the period		4,110
Settlements made during the period		(5,240	)
Increases in warranty estimates		190

Balance at September 30, 2017	$	4,750


Current portion	$	2,080
Non-current portion		2,670

Total	$	4,750

Stock-Based Compensation

Stock-based compensation cost is measured at the grant date based on the estimated fair value of the award, and the portion that is ultimately expected to vest is recognized as compensation expense over the requisite service period on a straight-line basis. The Company estimates the fair value of stock options issued under the Company’s 2013 Stock Incentive Plan (“2013 Plan”) and shares issued under the Company’s 2013 Employee Stock Purchase Plan (“ESPP”) using a Black-Scholes option-pricing model on the date of grant. The Black-Scholes option-pricing model requires the use of subjective assumptions about a number of key variables, including stock price volatility, expected term, and risk-free interest rate. For awards that vest based on the achievement of service conditions, the Company recognizes expense using the straight-line method less estimated forfeitures based on historical experience.

Net Loss Per Share

Diluted net loss per share is calculated by dividing the net loss by the sum of the weighted average number of common shares that were outstanding for the period and the weighted-average number of dilutive common share equivalents outstanding for the period determined using the treasury stock method. Dilutive common share equivalents are comprised of warrants, options outstanding under the Company’s equity incentive plans, and shares subject to issuance pursuant to the ESPP. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.

Potentially dilutive securities not included in the calculation of diluted net loss per share (because inclusion would be anti-dilutive) are as follows (in thousands, in common stock equivalent shares):


	Nine Months Ended September 30,
	2017		2016
Common stock warrants		—		99
Common stock options		3		262
ESPP		—		7

		3		368

Recent Accounting Pronouncements

In August 2016, the Financial Accounting Standards Board (“FASB”) issued new guidance that clarifies how entities should classify certain cash receipts and cash payments on the statement of cash flows. The guidance also clarifies how the predominance principle should be applied when cash receipts and cash payments have aspects of more than one class of cash flows. The guidance is effective for public companies for fiscal years beginning after December 15, 2017, and interim periods within those years. The Company does not believe the adoption of the standard will have a material impact on the Company’s statement of cash flow.

In June 2016, FASB issued a new credit loss standard that changes the impairment model for most financial assets and certain other instruments. The standard is effective for public business entities for annual periods beginning after December 15, 2019, and interim periods within those years. Early adoption is permitted for all entities for annual periods beginning after December 15, 2018, and interim periods within those years. The Company is in the process of assessing the impact of the adoption of the standard on its financial statements.

In March 2016, FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718) (“ASU 2016-09”), which is intended to simplify several areas of accounting for share-based payment arrangements. The amendments in this update cover such areas as the recognition of excess tax benefits and deficiencies, the classification of those excess benefits on the statement of cash flows, an accounting policy election for forfeitures, the amount an employer can withhold to cover income taxes and still qualify for equity classification and the classification of those taxes paid on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods. The Company adopted this standard in the first quarter of 2017. The Company had excess tax benefits for which a benefit could not previously be recognized of approximately $656,000 as of December 31, 2016. Upon adoption, the balance of the unrecognized excess tax benefits was reversed with the impact recorded to (accumulated deficit) retained earnings, including any change to the valuation allowance as a result of the adoption. Due to the full valuation allowance on the U.S. deferred tax assets as of December 31, 2016, there was no impact to the financial statements as a result of this adoption.

In February 2016, FASB issued final guidance for lease accounting. The new guidance requires lessees to put most leases on their balance sheet but to recognize expenses on their income statement in a manner similar to current accounting principles. The new guidance also eliminates the current real estate-specific provisions for all entities. The standard is effective for public companies for annual periods beginning after December 15, 2018, and interim periods within those years. Early adoption is permitted for all entities. The Company is in the process of assessing the impact of the adoption of the standard on its financial statements.

In May 2014, FASB and the International Accounting Standards Board issued a comprehensive new revenue recognition standard (“Revenue from Contracts with Customers Standard”) that will supersede existing revenue guidance under U.S. GAAP and International Financial Reporting Standards. The Revenue from Contracts with Customers Standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under current guidance. The Revenue from Contracts with Customers Standard will be effective for the Company beginning in its first quarter of 2018, and early adoption is permitted.

Subsequently, FASB issued the following standards related to Revenue from Contracts with Customers Standard: Principal versus Agent Considerations; Identifying Performance Obligations and Licensing; and Narrow-Scope Improvements and Practical Expedients (collectively, the “new revenue standards”). The new revenue standards may be applied retrospectively to each prior period presented (full retrospective method) or retrospectively with the cumulative effect recognized as of the date of adoption (the modified retrospective method). The Company currently expects to adopt the new revenue standards in the first quarter of 2018 utilizing the modified retrospective method. The Company currently believes that the adoption will not have a material impact on the recognition of revenues for the sale of its products through third-party distributors and insurance payors with whom it has contractual arrangements, which generally comprise approximately 99% of its sales. Additionally, the Company has given consideration to the accounting for warranty and commissions and does not anticipate a material change to its current method of expense recognition. As of September 30, 2017, the Company has not determined the full impact the adoption of the new revenue standard may have on its reported revenue or results of operations.

2. Summary of Significant Accounting Policies

Use of Estimates

The preparation of the financial statements in conformity with GAAP requires management to make informed estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities in the Company’s financial statements and accompanying notes as of the date of the financial statements. Actual results could differ materially from those estimates and assumptions.

Segment Reporting

Operating segments are identified as components of an enterprise about which segment discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. To date, the Company has viewed its operations and managed its business as one segment, operating in the United States.

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less from the date of purchase and that can be liquidated without prior notice or penalty, to be cash equivalents.

Short-Term Investments

Based on the nature of the assets, the Company’s short-term investments are classified as either available-for-sale or trading securities. Such securities are carried at fair value as determined by prices for identical or similar securities at the balance sheet date. The Company’s short-term investments consist of Level 1 and Level 2 financial instruments in the fair value hierarchy. The net unrealized gains or losses on available-for-sale securities are reported as a component of other comprehensive loss within the statements of operations and accumulated other comprehensive (loss) income as a separate component of stockholders’ equity (deficit) on the balance sheets. Unrealized gains or losses on trading securities are reported as a component of other income or expense within the statements of operations. At December 31, 2016 and 2015, the Company had no investments that were classified as held-to-maturity. The Company determines the realized gains or losses of available-for-sale securities using the specific identification method and includes net realized gains and losses as a component of other income or expense within the statements of operations. The Company periodically reviews available-for-sale securities for other than temporary declines in fair value below the cost basis whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. To date, no other than temporary declines in fair value have been identified.

Restricted Cash

Restricted cash as of December 31, 2016 and 2015 was comprised of a $2.0 million minimum cash balance requirement in connection with the Term Loan Agreement (see Note 5, “Term Loan Agreement”).

Accounts Receivable

The Company grants credit to various customers in the normal course of business. The Company maintains an allowance for doubtful accounts for potential credit losses. Provisions are made based on historical experience, assessment of specific risk, specific review of outstanding invoices or various assumptions and estimates that are believed to be reasonable under the circumstances. Uncollectible accounts are written off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a balance is uncollectible.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, short-term investments and accounts receivable. The Company maintains deposit accounts in federally insured financial institutions in excess of federally insured limits. The Company also maintains investments in money market funds that are not federally insured. Additionally, the Company has established guidelines regarding investment instruments and their maturities, which are designed to maintain preservation of principal and liquidity.

The following table summarizes customers who accounted for 10% or more of net accounts receivable:


	December 31,
	2016			2015
Edgepark Medical Supplies, Inc.		15.2	%		16.4	%
Byram Healthcare		14.7	%		21.8	%

The following table summarizes customers who accounted for 10% or more of sales for the periods presented:


	December 31,
	2016			2015			2014
Edgepark Medical Supplies, Inc.		18.7	%		17.8	%		16.0	%
Byram Healthcare		14.0	%		17.2	%		10.9	%
Solara Medical Supplies, Inc.		10.7	%		N/A			N/A
CCS Medical		N/A			N/A			11.6	%

Fair Value of Financial Instruments

The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable, accrued expense, and employee-related liabilities are reasonable estimates of their fair values because of the short-term nature of these assets and liabilities. Short-term investments and foreign exchange forward contracts that are not designated as hedges are carried at fair value. Based on the borrowing rates currently available for loans with similar terms, the Company believes that the fair value of its long-term notes payable approximates its carrying value.

The Company offers to certain eligible customers trade-in rights which are determined to be guarantees. The Company records a liability for the estimated fair value of the guarantee at its inception. If actual results differ significantly from these estimates, the Company’s results of operations could be materially affected. For further details regarding our guarantees, see the following section “Revenue Recognition” within Note 2 and Note 4, “Fair Value Measurements.”

Inventories

Inventories are valued at the lower of cost or market (net realizable value), determined by the first-in, first-out method. Inventory is recorded using standard cost, including material, labor and overhead costs, at December 31, 2016 and 2015. The Company periodically reviews inventories for potential impairment based on quantities on hand, expectations of future use, judgments based on quality control testing data and assessments of the likelihood of scrapping or obsoleting certain inventories.

Long Lived Assets

Property and Equipment

Property and equipment, which primarily consist of office furniture and equipment, manufacturing equipment, scientific equipment, computer equipment, and leasehold improvements, are stated at cost. Property and equipment are depreciated over the estimated useful lives of the assets, generally three to seven years, using the straight-line method. Leasehold improvements are amortized over the lesser of the estimated useful lives of the assets or the remaining lease term. Maintenance and repair costs are expensed as incurred.

Patents

Costs associated with the purchase or licensing of patents associated with the Company’s commercialized products are capitalized. The Company reviews its capitalized patent costs periodically to determine that they have future value and an alternative future use. Costs related to patents that the Company is not actively pursuing for commercial purposes are expensed. The Company amortizes patent costs over the lesser of the duration of the patent term or the estimated useful lives of 10 years, beginning with the date the patents are issued or acquired.

The Company periodically re-evaluates the original assumptions and rationale utilized in the establishment of the carrying value and estimated lives of all of its long-lived assets, including property and equipment and acquired patents. The determinants used for this evaluation include management’s estimate of the asset’s ability to generate positive income from operations and positive cash flow in future periods as well as the strategic significance of the asset to the Company’s business objective. The Company has not recognized any impairment losses through December 31, 2016.

Deferred Rent

Rent expense on noncancelable leases containing known future scheduled rent increases is recorded on a straight-line basis over the term of the respective leases beginning when the Company takes possession of the leased property. The difference between rent expense and rent paid is accounted for as deferred rent. The current portion of deferred rent was included in other current liabilities on the Company’s balance sheet. Landlord improvement allowances and other such lease incentives are recorded as property and equipment and as deferred rent and are amortized on a straight-line basis as a reduction to rent expense.

Research and Development Costs

All research and development costs are charged to expense as incurred. Such costs include personnel-related costs, including stock-based compensation, supplies, license fees, development prototypes, outside design and testing services, depreciation, allocated facilities and information services, milestone payments under the Company’s development and commercialization agreements and other indirect costs.

Income Taxes

The Company uses the asset and liability method of accounting for income taxes. Deferred income tax assets or liabilities are recognized based on the temporary differences between financial statement and income tax bases of assets and liabilities using enacted tax rates in effect for the years in which the differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized.

The Company is required to file federal and state income tax returns in the United States and various other state jurisdictions. The preparation of these income tax returns requires the Company to interpret the applicable tax laws and regulations in effect in such jurisdictions, which could affect the amount of tax paid by the Company. An amount is accrued for the estimate of additional tax liability, including interest and penalties, for any uncertain tax positions taken or expected to be taken in an income tax return. The Company reviews and updates the accrual for uncertain tax positions as more definitive information becomes available. For further information, see Note 7, “Income Taxes.”

Revenue Recognition

Revenue is generated from sales in the United States of insulin pumps, disposable cartridges and infusion sets to individual customers and third-party distributors that resell the product to insulin-dependent diabetes customers. The Company is paid directly by customers who use the products, distributors and third-party insurance payors.

Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred and title passed, the price is fixed or determinable, and collectability is reasonably assured.

Trade-In Rights

The trade-in rights associated with the Company’s Technology Upgrade Program are accounted for as guarantees or rights to return based on specific factors and circumstances, including the period of time the trade-in rights are exercisable, the likelihood that the trade-in rights will be exercised, and the amount of the specified-price trade-in value.

The Company has determined that trade-in rights for t:slim G4 Pump customers are guarantees. The Company accounts for the guarantees under applicable accounting standards, which require a guarantor to recognize, at the inception of a guarantee, a liability for the estimated fair value of the obligation undertaken in issuing certain guarantees. Subsequently, the initial liability recognized for the guarantee is reduced as the Company is released from the risk under the guarantee, which is when the trade-in right is exercised or the right expires. The guarantee is accounted for as an element of a multiple element arrangement. The estimated fair value of the guarantees are based on various economic and customer behavioral assumptions, including the probability of a trade-in, the specified trade-in amount, the expected fair value of the used t:slim G4 Pump at trade-in and the expected sales price of the t:slim X2 Pump. At December 31, 2016, $1.2 million was recorded as a guarantee liability in other current liabilities on the accompanying balance sheet.

The Company has determined that t:slim Pump trade-in rights are in-substance rights to return products. Such rights to return are accounted for pursuant to the right of return accounting guidance. As the Company does not have sufficient history to reasonably estimate returns associated with trade-in rights, all eligible t:slim Pump sales between July 1, 2016 and December 31, 2016 were recorded as deferred revenue until the trade-in right is exercised or the right expires. At December 31, 2016, $3.2 million was recorded as a trade-in rights reserve in deferred revenue on the accompanying balance sheet.

Revenue Recognition for Arrangements with Multiple Deliverables

The Company considers the deliverables in its product offering as separate units of accounting and recognizes deliverables as revenue upon delivery only if (i) the deliverable has standalone value and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is probable and substantially controlled by the Company. The Company allocates consideration to the separate units of accounting, unless the undelivered elements were deemed perfunctory and inconsequential. The amount of the determined guarantee fair value is allocated in full to the guarantee and the remaining allocable consideration is allocated to other separate units of accounting using the relative selling price method, in which allocation of consideration is based on vendor-specific objective evidence (“VSOE”) if available, third-party evidence (“TPE”), or if VSOE and TPE are not available, management’s best estimate of a standalone selling price (“ESP”) for the undelivered elements.

The Company offers a cloud-based data management application, t:connect, which is made available to customers upon purchase of any of its insulin pumps. In July 2016, the Company received clearance from the FDA to begin offering the Tandem Device Updater, a Mac and PC-compatible tool for the remote update of Tandem insulin pump software. Utilizing Tandem Device Updater, the Company may from time to time provide future unspecified software upgrades to the insulin pump’s essential software. The t:connect service and the embedded right included with qualifying insulin pumps to receive, on a when-and-if-available basis, future unspecified software upgrades relating to the product’s essential software are deemed undelivered elements at the time of the insulin pump sale. Because the Company has neither VSOE nor TPE for these deliverables, the allocation of revenue is based on the Company’s ESP. The Company establishes its ESP based on the estimated cost to provide such services, including consideration for a reasonable profit margin, which is then corroborated by comparable market data. The Company allocates fair value based on management’s ESP to these elements at the time of sale and recognizes the revenue over a four-year period, which is the hosting period for t:connect and the period that software upgrades are expected to be provided. At December 31, 2016 and 2015, $1.6 million and $1.1 million were recorded as deferred revenue for these undelivered elements, respectively. All other undelivered elements at the time of sale are deemed inconsequential or perfunctory.

Product Returns

The Company offers a 30-day right of return to its customers from the date of shipment of any of its insulin pumps, provided a physician’s confirmation of the medical reason for the return is received. Estimated allowances for sales returns are based on historical returned quantities as compared to pump shipments in those same periods of return. The return rate is then applied to the sales of the current period to establish a reserve at the end of the period. The return rates used in the reserve are adjusted for known or expected changes in the marketplace when appropriate. The allowance for product returns is recorded as a reduction of revenue and accounts receivable in the period in which the related sale is recorded. The amount recorded on the Company’s balance sheet for product return allowance was $0.2 million and $0.3 million at December 31, 2016 and 2015, respectively. Actual product returns have not differed materially from estimated amounts reserved in the accompanying financial statements.

Warranty Reserve

The Company generally provides a four-year warranty on its insulin pumps to end user customers and may replace any pumps that do not function in accordance with the product specifications. Insulin pumps returned to the Company may be refurbished and redeployed. Additionally, the Company offers a six-month warranty on disposable cartridges and infusion sets. Estimated warranty costs are recorded at the time of shipment. Warranty costs are estimated based on the current expected replacement product cost and expected replacement rates based on historical experience. The Company evaluates the reserve quarterly and makes adjustments when appropriate. Changes to the actual replacement rates and actual replacement product costs could have a material impact on the Company’s estimated liability.

At December 31, 2016 and December 31, 2015, the warranty reserve was $5.7 million and $3.5 million, respectively. The following table provides a reconciliation of the change in estimated warranty liabilities for the years ended December 31, 2016 and 2015:


	December 31,
(in thousands)	2016			2015
Balance at beginning of the year	$	3,547		$	1,974
Provision for warranties issued during the period		8,830			1,948
Settlements made during the period		(8,739	)		(4,373	)
Increases in warranty estimates		2,052			3,998

Balance at end of the year	$	5,690		$	3,547

Current portion	$	2,302		$	1,050
Non-current portion	$	3,388			2,497

Total	$	5,690		$	3,547

Stock-Based Compensation

Stock-based compensation cost is measured at the grant date based on the estimated fair value of the award, and the portion that is ultimately expected to vest is recognized as compensation expense over the requisite service period on a straight-line basis. The Company estimates the fair value of stock options issued under the Company’s 2013 Stock Incentive Plan (“2013 Plan”) and shares issued under the Company’s 2013 Employee Stock Purchase Plan (“ESPP”) using a Black-Scholes option-pricing model on the date of grant. The Black-Scholes option-pricing model requires the use of subjective assumptions including volatility, expected term, and risk-free rate. For awards that vest based on service conditions, the Company recognizes expense using the straight-line method less estimated forfeitures based on historical experience.

The Company records the expense for stock option grants to non-employees based on the estimated fair value of the stock options using the Black-Scholes option-pricing model. The fair value of non-employee awards is remeasured at each reporting period as the underlying awards vest unless the instruments are fully vested, immediately exercisable and nonforfeitable on the date of grant.

Advertising Costs

The Company expenses advertising costs as they are incurred. For the years ended December 31, 2016, 2015 and 2014, advertising costs were $0.9 million, $1.0 million, and $1.5 million, respectively.

Shipping and Handling Expenses

Shipping and handling expenses associated with product delivery are included within cost of sales in the Company’s statements of operations.

Comprehensive Loss

All components of comprehensive loss, including net loss, are reported in the financial statements in the period in which they are recognized. Comprehensive loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares that were outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by dividing the net loss by the sum of the weighted-average number of dilutive common share equivalents outstanding for the period determined using the treasury stock method. Dilutive common share equivalents are comprised of warrants, potential awards granted pursuant to the ESPP, and options outstanding under the Company’s other equity incentive plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.

Potentially dilutive securities not included in the calculation of diluted net loss per share (because inclusion would be anti-dilutive) are as follows (in common stock equivalent shares, in thousands):


	Year Ended December 31,
	2016		2015		2014
Warrants for common stock		—		99		100
Common stock options		151		201		223
ESPP		2		0		0

		153		3,00		323

Reclassifications

Certain reclassifications of prior year amounts have been made to conform to the current year presentation.

Recent Accounting Pronouncements

In August 2016, the Financial Accounting Standards Board (“FASB”) issued new guidance that clarifies how entities should classify certain cash receipts and cash payments on the statement of cash flows. The guidance also clarifies how the predominance principle should be applied when cash receipts and cash payments have aspects of more than one class of cash flows. The guidance is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those years. The Company does not believe the adoption of the standard will have a material impact on the Company’s statement of cash flow.

In March 2016, FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718) (“ASU 2016-09”), which is intended to simplify several areas of accounting for share-based payment arrangements. The amendments in this update cover such areas as the recognition of excess tax benefits and deficiencies, the classification of those excess benefits on the statement of cash flows, an accounting policy election for forfeitures, the amount an employer can withhold to cover income taxes and still qualify for equity classification and the classification of those taxes paid on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods. The Company will adopt this standard beginning in the first quarter of 2017. The Company has excess tax benefits for which a benefit could not previously be recognized of approximately $656,000. Upon adoption, the balance of the unrecognized excess tax benefits will be reversed with the impact recorded to (accumulated deficit) retained earnings, including any change to the valuation allowance as a result of the adoption. Due to the full valuation allowance on the U.S. deferred tax assets as of December 31, 2016, the Company does not expect any impact to the financial statements as a result of this adoption in the first quarter of 2017.

In February 2016, FASB issued final guidance for lease accounting. The new guidance requires lessees to put most leases on their balance sheet but to recognize expenses on their income statement in a manner similar to today’s accounting. The new guidance also eliminates today’s real estate-specific provisions for all entities. The standard is effective for public business entities for annual periods beginning after December 15, 2018, and interim periods within those years. Early adoption is permitted for all entities. The Company is in the process of assessing the impact of the adoption of the standard on its financial statements.

In April 2015, FASB issued new guidance, which amended requirements that require debt issuance costs, related to a recognized debt liability, to be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, effective for the Company beginning January 1, 2016 and applied retroactively for all consolidated balance sheets presented. The Company applied the amended presentation requirements in the first quarter 2016, which resulted in the reclassification of $0.4 million of debt issuance costs in the Company’s balance sheet from other long-term assets to long-term notes payable at December 31, 2015.

In August 2014, FASB issued an accounting standards update, which requires management of public and private companies to evaluate whether there are conditions and events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the financial statements are issued (or available to be issued when applicable) and, if so, to disclose that fact. Management is required to make this evaluation for both annual and interim reporting periods, if applicable. Management is also required to evaluate and disclose whether its plans alleviate that doubt. The standard is effective for annual periods ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016. The Company adopted this standard as of December 31, 2016 and has included the expanded discussion on going concern above (see Note 1 “The Company”).

The new revenue standards may be applied retrospectively to each prior period presented (full retrospective method) or retrospectively with the cumulative effect recognized as of the date of adoption (the modified retrospective method). The Company currently expects to adopt the new revenue standards in its first quarter of 2018 utilizing the modified retrospective method. The Company has begun assessing the impact of the adoption of the new revenue standards on its financial statements, and will not know whether there will be any impact of adoption until its assessment is completed sometime later in 2017.

Short-Term Investments

9 Months Ended

Sep. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

3. Short-Term Investments

The Company invests in investment securities, principally debt instruments of financial institutions and corporations with strong credit ratings. The following represents a summary of the estimated fair value of short-term investments at September 30, 2017 and December 31, 2016 (in thousands):


At September 30, 2017	Maturity (in years)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants		$	416	$	43	$	—	$	459

Total		$	416	$	43	$	—	$	459


At December 31, 2016	Maturity (in years)		Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper		Less than 1	$	8,483	$	1	$	(2	)	$	8,482
Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants			$	354	$	26	$	(2	)	$	378

Total			$	8,837	$	27	$	(4	)	$	8,860

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Inventory

9 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

Inventory

4. Inventory

Inventory consisted of the following at September 30, 2017 and December 31, 2016 (in thousands):


	September 30, 2017		December 31, 2016
Raw materials	$	10,138	$	9,375
Work in process		5,497		4,395
Finished goods		14,350		7,425

Total	$	29,985	$	21,195

The increase in inventory at September 30, 2017 as compared to December 31, 2016 is primarily due to an increase in infusion set finished goods in connection with the commercial launch of the t:lock infusion set.

Fair Value Measurements

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value Measurements

5. Fair Value Measurements

Authoritative guidance on fair value measurements defines fair value, establishes a consistent framework for measuring fair value, and expands disclosures for each major asset and liability category measured at fair value on either a recurring or a nonrecurring basis. Fair value is intended to reflect an assumed exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the authoritative guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:


Level 1:		Observable inputs such as unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.

Level 2:		Inputs, other than quoted prices in active markets, that are observable either directly or indirectly for substantially the full term of the asset or liability.

Level 3:		Unobservable inputs in which there is little or no market data and that are significant to the fair value of the assets or liabilities, which require the reporting entity to develop its own valuation techniques that require input assumptions.

The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of September 30, 2017 and December 31, 2016, and indicates the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair value (in thousands):


			Fair Value Measurements at September 30, 2017
			(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents⁽¹⁾	$	16,527	$	16,527	$	—	$	—
Mutual funds held for nonqualified deferred compensation plan participants⁽²⁾		459		459		—		—

Total assets	$	16,986	$	16,986	$	—	$	—

Liabilities
Deferred compensation⁽²⁾	$	459	$	459	$	—	$	—

Total liabilities	$	459	$	459	$	—	$	—


			Fair Value Measurements at December 31, 2016
			(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents⁽¹⁾	$	39,941	$	39,941	$	—	$	—
Commercial paper		8,482		—		8,482		—
Mutual funds held for nonqualified deferred compensation plan participants⁽²⁾		378		378		—		—

Total assets	$	48,801	$	40,319	$	8,482	$	—

Liabilities
Deferred compensation⁽²⁾	$	378	$	378	$	—	$	—

Total liabilities	$	378	$	378	$	—	$	—

⁽¹⁾

Generally, cash equivalents include money market funds and investments with a maturity of three months or less from the date of purchase. This asset is included as a component of cash and cash equivalents on the balance sheet, of which $10.0 million is classified as restricted cash—long-term at September 30, 2017.

⁽²⁾

The deferred compensation plan is directed by the Company and structured as a Rabbi Trust for the benefit of certain executives and non-employee directors. The investment assets of the Rabbi Trust are valued using quoted market prices multiplied by the number of shares held in each trust account. The related deferred compensation liability represents the fair value of the investment assets.

The Company’s Level 2 financial instruments are valued using market prices on less active markets with observable valuation inputs such as interest rates and yield curves. The Company obtains the fair value of Level 2 financial instruments from quoted market prices, calculated prices or quotes from third-party pricing services. The Company validates these prices through independent valuation testing and review of portfolio valuations provided by the Company’s investment managers. There were no transfers between Level 1 and Level 2 assets during the nine months ended September 30, 2017.

The Company recorded $1.2 million as guarantee liabilities in other current liabilities on the accompanying condensed balance sheet at December 31, 2016. There were no guarantee liabilities at September 30, 2017. Guarantees were recorded as a reduction of revenue in the statement of operations and other comprehensive loss. Guarantees are not measured at fair value on a recurring basis, and therefore are not included in the tables above. Guarantees are classified within Level 3 of the fair value hierarchy. The estimated fair value of the guarantees is based on various economic and customer behavioral assumptions, including the probability that a trade-in right will be exercised, the specified trade-in amount, the expected fair value of the used t:slim G4 Pump at trade-in and the expected sales price of t:slim X2 (see Note 2, “Summary of Significant Accounting Policies—Revenue Recognition”). Changes in the probability that a trade-in right will be exercised have the most significant impact on the estimate of the fair value of the liabilities.

In connection with the Term Loan Agreement, on March 7, 2017, the Company issued ten-year warrants to purchase 193,788 shares of the Company’s common stock at an exercise price of $23.50 per share (the “Capital Royalty Warrant”). The Company used the Black-Scholes option-pricing model to calculate the value of the Capital Royalty Warrant of approximately $3.3 million. The Capital Royalty Warrant was recorded as debt discount and stockholders’ equity, as the warrants met the definition of an equity instrument. The Black-Scholes option-pricing model requires the use of subjective assumptions about a number of key variables, including stock price volatility, expected term, and risk-free interest rate.

4. Fair Value Measurements

Authoritative guidance on fair value measurements defines fair value, establishes a consistent framework for measuring fair value, and expands disclosures for each major asset and liability category measured at fair value on either a recurring or a nonrecurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the authoritative guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:


Level 1:		Observable inputs such as unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.

Level 2:		Inputs, other than quoted prices in active markets, that are observable either directly or indirectly for substantially the full term of the asset or liability.

Level 3:		Unobservable inputs in which there is little or no market data and that are significant to the fair value of the assets or liabilities, which require the reporting entity to develop its own valuation techniques that require input assumptions.

The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2016 and 2015, and indicates the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair value (in thousands):


			Fair Value Measurements at December 31, 2016
	December 31, 2016		Level 1		Level 2		Level 3
Assets
Cash equivalents⁽¹⁾	$	39,941	$	39,941	$	—	$	—
Commercial paper		8,482		—		8,482		—
Mutual funds held for nonqualified deferred compensation plan participants⁽²⁾		378		378		—		—

Total assets	$	48,801	$	40,319	$	8,482	$	—

Liabilities
Deferred compensation⁽²⁾	$	378	$	378	$	—	$	—

Total liabilities	$	378	$	378	$	—	$	—


			Fair Value Measurements at December 31, 2015
	December 31, 2015		Level 1		Level 2		Level 3
Assets
Cash equivalents⁽¹⁾	$	23,402	$	23,402	$	—	$	—
Commercial paper		21,735		—		21,735		—
Mutual funds held for nonqualified deferred compensation plan participants⁽²⁾		222		222		—		—
Treasury securities		2,034		2,034		—		—
Government-sponsored enterprise securities		4,027		—		4,027		—

Total assets	$	51,420	$	25,658	$	25,762	$	—

Liabilities
Deferred compensation⁽²⁾	$	222	$	222	$	—	$	—

Total liabilities	$	222	$	222	$	—	$	—

⁽¹⁾	Cash equivalents included money market funds and commercial paper with a maturity of three months or less from the date of purchase.

⁽²⁾

Deferred compensation plans are compensation plans directed by the Company and structured as a Rabbi Trust for certain executives and non-employee directors. The investment assets of the Rabbi Trust are valued using quoted market prices multiplied by the number of shares held in each trust account. The related deferred compensation liability represents the fair value of the investment assets.

The Company’s Level 2 financial instruments are valued using market prices on less active markets with observable valuation inputs such as interest rates and yield curves. The Company obtains the fair value of Level 2 financial instruments from quoted market prices, calculated prices or quotes from third-party pricing services. The Company validates these prices through independent valuation testing and review of portfolio valuations provided by the Company’s investment managers. There were no transfers between Level 1 and Level 2 securities during the years ended December 31, 2016 and 2015.

As of December 31, 2016, the Company recorded a $1.2 million as a guarantee liability in other current liabilities on the accompanying balance sheet, and as a reduction of revenue in the statement of operations and other comprehensive loss. Guarantees are not measured at fair value on a recurring basis; they are not included in the tables above. Guarantees are classified within Level 3 of the fair value hierarchy. The estimated fair value of the guarantee is based on various economic and customer behavioral assumptions, including the probability that a trade-in right will be exercised, the specified trade-in amount, the expected fair value of the used t:slim G4 Pump at trade-in and the expected sales price of the t:slim X2 Pump (see Note 2, “Summary of Significant Accounting Policies—Revenue Recognition”). Changes in the probability of the trade-in have the most significant impact on the estimate of the fair value of the liability.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Term Loan Agreement

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Debt Disclosure [Abstract]

Term Loan Agreement

6. Term Loan Agreement

The Company had $82.3 million and $81.1 million of aggregate borrowings outstanding under the Term Loan Agreement, at September 30, 2017 and December 31, 2016, respectively.

Under the Term Loan Agreement, interest is payable at the Company’s option, (i) in cash at a rate of 11.5% per annum, or (ii) at a rate of 9.5% of the 11.5% per annum in cash and 2.0% of the 11.5% per annum (the “PIK Loan”) to be added to the principal of the loan and subject to accruing interest. Interest-only payments are due quarterly on March 31, June 30, September 30 and December 31 of each year of the interest-only payment period, which ends on December 31, 2019. The principal balance is due in full at the end of the term of the loan, which is March 31, 2020 (the “Maturity Date”). The Company had elected to pay interest in cash at a rate of 11.5% per annum through September 30, 2015. Beginning October 1, 2015, the Company elected to pay interest in cash at a rate of 9.5% per annum and for a rate of 2.0% per annum to be added to the principal of the loan. As a result, $2.3 million was added to the principal of the loan since October 1, 2015, which the Company refers to as PIK Loans.

The term loan is collateralized by all assets of the Company. The principal financial covenants require that the Company attain minimum annual revenues of $80.0 million in 2017 and $95.0 million each year thereafter until the Maturity Date.

Pursuant to Amendment No. 3 to Term Loan Agreement (the “Third Amendment”), the Company agreed to pay, on the earlier of (i) the Maturity Date, (ii) the date that the loan under the Term Loan Agreement becomes due, and (iii) the date on which the Company makes a voluntary pre-payment of the loan, a financing fee equal to 3.0% of the sum of (x) the aggregate amount drawn under the Third Amendment, which is $50.0 million, and (y) any PIK Loans issued in relation to the Third Amendment (collectively, the “Back End Financing Fee”).

The audit report of the Company’s independent registered public accounting firm contained in the Annual Report included an explanatory paragraph that describes conditions that raise substantial doubt about the Company’s ability to continue as a going concern. This explanatory paragraph constituted a potential event of default under the Term Loan Agreement. On March 7, 2017, the Company entered into Waiver and Amendment No. 4 to the Term Loan Agreement (the “Fourth Amendment”), which included a limited waiver of the potential event of default that could have resulted from the explanatory paragraph. In consideration for the waiver, the Company agreed to: (i) issue the Capital Royalty Warrant, (ii) increase its restricted cash balance from $2.0 million to $10.0 million, (iii) provide Capital Royalty Partners the same information it makes available to its board of directors, subject to limited exceptions, and (iv) not incur additional third party indebtedness secured solely by accounts receivable, inventory and cash. In addition, the Fourth Amendment includes a covenant requiring the Company to complete financings in which its gross proceeds from the sale of equity securities is at least $30.0 million, no later than January 15, 2018. Furthermore, the Company agreed to increase the Back End Financing Fee to 5.0% of the entire aggregate principal amount of borrowings outstanding, including total PIK Loans issued. The Back End Financing Fee is payable at maturity of the Company’s loans and on the principal amount of any loans for which it makes an optional prepayment, and may be payable in connection with certain asset sales or a change of control.

As of September 30, 2017 and December 31, 2016, respectively, the Company had accrued $4.1 million and $1.5 million for the Back End Financing Fee in other long-term liabilities and as contra-debt in notes payable-long-term on the accompanying condensed balance sheets.

The Company evaluated execution of the Fourth Amendment as a modification for accounting purposes and concluded that it did not constitute a modification because the present value of the future cash flows under the Fourth Amendment did not exceed the present value of the future cash flows under the previous terms by more than 10%. The Back End Financing Fee, the value of the Capital Royalty Warrant, and the remaining balance of debt issuance costs and debt discount of the loan are amortized to interest expense over the remaining term of the Term Loan Agreement using the effective interest method.

5. Term Loan Agreement

At December 31, 2015, the Company had $30.2 million aggregate borrowings outstanding under the Term Loan Agreement. In January 2016, the Company entered into Amendment No. 3 to the Term Loan Agreement (the “Third Amendment”) which allowed the Company to borrow up to an additional $50.0 million. The Company borrowed $15.0 million of this amount in January 2016 and the remaining $35.0 million in December 2016. At December 31, 2016, the Company had $81.1 million of aggregate borrowings outstanding under the Term Loan Agreement.

The other principal terms of the Term Loan Agreement were not amended by the Third Amendment. Accordingly, interest continues to be payable, at the Company’s option, (i) in cash at a rate of 11.5% per annum, or (ii) at a rate of 9.5% of the 11.5% per annum in cash and 2.0% of the 11.5% per annum (the “PIK Loan”) to be added to the principal of the loan and subject to accruing interest. Interest-only payments continue to be due quarterly on March 31, June 30, September 30 and December 31 of each year of the interest-only payment period, which ends on December 31, 2019. The principal balance continues to be due in full at the end of the term of the loan, which is March 31, 2020 (the “Maturity Date”). The Company had elected to pay interest in cash at a rate of 11.5% per annum through September 30, 2015. Beginning October 1, 2015, the Company elected to pay interest in cash at a rate of 9.5% per annum and for a rate of 2.0% per annum to be added to the principal of the loan. As a result, $0.9 million and $0.2 million was added to the principal of the loan for the year ended December 31, 2016 and three months ended December 31, 2015, respectively. which the Company refers to as PIK Loans.

The Term Loan Agreement provides for prepayment fees in an amount equal to one percent (1.0%) of the outstanding balance of the loan if the loan is repaid prior to March 31, 2017, after which there is no prepayment fee. The term loan is collateralized by all assets of the Company. The principal financial covenants continue to require that the Company attain minimum annual revenues of $65.0 million in 2016, $80.0 million in 2017 and $95.0 million each year thereafter until the Maturity Date.

Pursuant to the Third Amendment, the Company has agreed to pay, on the earlier of (i) the Maturity Date, (ii) the date that the loan under the Term Loan Agreement becomes due, and (iii) the date on which the Company makes a voluntary pre-payment of the loan, a financing fee equal to 3.0% of the sum of (x) the aggregate amount drawn under the Third Amendment, and (y) any PIK Loans issued in relation to the Third Amendment (collectively, the “Back End Financing Fee”). As of December 31, 2016, the Company had accrued $1.5 million for the Back End Financing Fee in other long-term liabilities and as contra-debt in notes payable-long-term on the accompanying balance sheet.

The Company treated execution of the Third Amendment as a modification for accounting purposes. The present value of the future cash flows under the Third Amendment did not exceed the present value of the future cash flows under the previous terms by more than 10%. The Back End Financing Fee and the remaining balance of debt issuance costs and debt discount of the loan are amortized to interest expense over the remaining term of the Third Amendment using the effective interest method.

Future minimum principal payments under the Term Loan Agreement as of December 31, 2016, are as follows (in thousands):


Year ended December 31,
2017	$	—
2018		—
2019		—
2020		81,080
2021		—
Thereafter		—

Total	$	81,080
Less current portion of notes payable		—

Notes payable, net of current portion	$	81,080

The audit report and opinion of the Company’s independent registered public accounting firm contained in the accompanying financial statements includes an explanatory paragraph that describes conditions that raise substantial doubt about its ability to continue as a going concern. This explanatory paragraph included in the report of the Company’s independent registered public accounting firm could constitute a potential event of default under the Term Loan Agreement. On March 7, 2017, the Company entered into the Fourth Amendment, which includes a limited waiver of a potential event of default that could have resulted from the explanatory paragraph. In consideration for the waiver, the Company agreed to: (i) issue Capital Royalty Partners ten-year warrants to purchase an aggregate of 1,937,890 shares of its common stock at an exercise price equal to $2.35 per share, the closing price of its common stock on the NASDAQ Global Market on the date of the Fourth Amendment, (ii) increase its minimum cash balance requirement under the Term Loan Agreement from $2.0 million to $10.0 million, (iii) provide Capital Royalty Partners the same information it makes available to its board of directors, subject to limited exceptions, and (iv) not incur additional third party indebtedness secured solely by accounts receivable, inventory and cash. In addition, the Fourth Amendment includes a covenant requiring the Company to complete a financing in which its gross proceeds from the sale of equity securities is at least $30.0 million, no later than January 15, 2018. Furthermore, the Company has agreed to increase the Back End Financing Fee to 5.0% of the entire aggregate principal amount of borrowings outstanding, including total PIK Loans issued, under the Term Loan Agreement, which was $81.1 million as of December 31, 2016. The Back End Financing Fee is payable at maturity of the Company’s loans and on the principal amount of any loans for which it makes an optional prepayment, and may be payable in connection with asset sales not permitted under the Term Loan Agreement or in connection with a change of control.

Stockholders' Equity (Deficit)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Equity [Abstract]

Stockholders' Equity (Deficit)

7. Stockholders’ Equity

Public Offering

In the first quarter of 2017, the Company completed a public offering of 1,850,000 shares of its common stock at a public offering price of $12.50 per share. The gross proceeds to the Company from the offering were $23.1 million, before deducting underwriting discounts and commissions and other offering expenses payable by the Company.

At The Market (ATM) Program

In July 2017, the Company entered into an Equity Distribution Agreement implementing an ATM program for aggregate gross proceeds up to $15.0 million. During the nine months ended September 30, 2017, the Company sold 464,108 shares of common stock under the ATM program at prices ranging from $5.64 to $10.54. The gross proceeds to the Company from these sales were $4.3 million, before deducting underwriting discounts and commissions and other offering expenses payable by the Company.

Shares Reserved for Future Issuance

The following shares of the Company’s common stock were reserved for future issuance at September 30, 2017 (in thousands):


Shares underlying outstanding warrants			293
Shares underlying outstanding stock options			933
Shares authorized for future equity award grants			39
Shares authorized for issuance as ESPP awards			—

			1,265

The Company issued 24,408 shares of its common stock upon the exercise of stock options during the nine months ended September 30, 2017, and issued 14,897 shares of its common stock upon the exercise of stock options during the year ended December 31, 2016.

The ESPP enables eligible employees to purchase shares of the Company’s common stock using their after tax payroll deductions, subject to certain conditions. The ESPP consists of a two-year offering period with four six-month purchase periods which begin in May and November of each year. There were 38,929 shares of the Company’s common stock purchased under the ESPP during the nine months ended September 30, 2017, and 69,502 shares of the Company’s common stock purchased under the ESPP during the year ended December 31, 2016.

The Company announced the suspension of the ESPP as of May 16, 2017 due to a lack of available shares. The suspension was accounted for as a cancellation of an award with no consideration. The previously unrecognized compensation cost as of the suspension date of $2.4 million was fully expensed during the second quarter of 2017.

Stock-Based Compensation

The assumptions used in the Black-Scholes option-pricing model are as follows:


	Stock Options
	Nine Months Ended September 30,
	2017			2016
Weighted average grant date fair value (per share)	$	5.10		$	37.80
Risk-free interest rate		1.9	%		1.4	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		60.0	%		55.5	%
Expected term (in years)		6.1			6.1


	ESPP
	Nine Months Ended September 30,
	2017⁽¹⁾		2016
Weighted average grant date fair value (per share)		N/A	$	26.90
Risk-free interest rate		N/A		0.6	%
Expected dividend yield		N/A		0.0	%
Expected volatility		N/A		56.9	%
Expected term (in years)		N/A		1.3

⁽¹⁾	There were no grants made pursuant to the ESPP during the nine months ended September 30, 2017.

The following table summarizes the allocation of stock-based compensation expense (in thousands):


	Nine Months Ended September 30,
	2017		2016
Cost of sales	$	1,022	$	776
Selling, general & administrative		8,423		6,992
Research and development		1,057		965

Total	$	10,502	$	8,733

The total stock-based compensation expense capitalized as part of the cost of inventory was $0.3 million and $0.2 million at September 30, 2017 and December 31, 2016, respectively.

6. Stockholders’ Equity (Deficit)

Public Offerings

In the first quarter of 2015, the Company completed a public offering of 603,750 shares of its common stock at a public offering price of $115.00 per share. Net cash proceeds from the public offering were approximately $64.9 million, after deducting underwriting discounts, commissions and offering expenses payable by the Company.

Stock Plans

In September 2006, the Company adopted the Company’s 2006 Stock Incentive Plan (the “2006 Plan”) under which, as amended, 268,560 shares of common stock were reserved for issuance to employees, non-employee directors and consultants of the Company. The 2006 Plan was closed in 2013 with the approval of the 2013 Plan and no further options will be granted under the 2006 Plan.

In October 2013, the Company’s board of directors approved the 2013 Plan. The 2013 Plan became effective immediately prior to the completion of the initial public offering. An initial 480,900 shares of common stock were reserved for issuance under the 2013 Plan. Under the 2013 Plan, the Company may grant stock options, stock appreciation rights, restricted stock and restricted stock units to individuals who are then employees, officers, directors or consultants of the Company. The shares available for issuance under the 2013 Plan were increased by 124,382 shares and 121,018 shares on January 1, 2017 and 2016, respectively, in accordance with an “evergreen” provision under the 2013 Plan.

As of December 31, 2016, 56,228 shares are available for future issuance under the 2013 Plan, and options to purchase 822,838 shares have been granted and are outstanding under the 2006 Plan and 2013 Plan.

Common Stock Options

The maximum term of stock options granted under the 2006 Plan and 2013 Plan is ten years. The options generally vest 25% on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years.

The following table summarizes stock option activities for the 2006 Plan and 2013 Plan:


	Total Options			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2014		501,106		$	102.04		8.62	$	23,534
Granted		117,557		$	120.06
Exercised		(24,355	)	$	13.82			$	2,540
Canceled/forfeited/expired		(19,408	)	$	168.63

Outstanding at December 31, 2015		574,900		$	107.22		7.99	$	19,158

Granted		316,671		$	45.75
Exercised		(14,876	)	$	11.49			$	1,049
Canceled/forfeited/expired		(53,857	)	$	126.19

Outstanding at December 31, 2016		822,838		$	84.05		7.92	$	1,593

Vested and expected to vest at December 31, 2016		812,862		$	84.24		7.91	$	1,592
Exercisable at December 31, 2016		423,810		$	98.61		6.80	$	1,554

Employee Stock Purchase Plan

In October 2013, the Company adopted the ESPP, which enables eligible employees to purchase shares of the Company’s common stock using their after tax payroll deductions, subject to certain conditions.

The ESPP initially authorized the issuance of 55,600 shares of common stock pursuant to purchase rights granted to employees. The number of shares of common stock reserved for issuance increases on January 1 of each calendar year, from January 1, 2014 through January 1, 2023, by the lesser of (a) one percent (1%) of the number of shares issued and outstanding on the immediately preceding December 31, or (b) such lesser number of shares as determined by the Administrator. On January 1, 2017 and 2016, the number of shares of common stock reserved for issuance under the ESPP was automatically increased by 31,095 shares and 30,254 shares, respectively. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Code. In the years ended December 31, 2016 and 2015, 69,233 shares and 30,218 shares of our common stock, respectively, were purchased under the ESPP. As of December 31, 2016, 7,846 shares remain available for issuance under the ESPP.

Eligible employees may contribute, normally through payroll deductions, up to 15% of their earnings for the purchase of common stock under the ESPP. The purchase price of common stock under the ESPP will be the lesser of: (a) 85% of the fair market value of a share of the Company’s common stock on the first date of an offering or (b) 85% of the fair market value of a share of the Company’s common stock on the date of purchase. Generally, the ESPP consists of a two-year offering period with four six-month purchase periods.

Stock-Based Compensation.

The compensation cost that has been included in the statement of operations for all stock-based compensation arrangements was as follows (in thousands):


	Year Ended December 31,
	2016		2015		2014
Cost of sales	$	1,016	$	1,162	$	1,317
Selling, general & administrative		9,360		10,517		11,886
Research and development		1,284		1,417		1,792

Total	$	11,660	$	13,096	$	14,995

The total stock-based compensation capitalized as part of the cost of the Company’s inventory was $0.2 million and $0.1 million at December 31, 2016 and 2015, respectively.

For the years ended December 31, 2016, 2015 and 2014, the expense for stock option grants to non-employees was zero, $35,000 and $0.3 million, respectively, and are included in the table above as a component of selling, general and administrative expenses.

At December 31, 2016, the total unamortized stock-based compensation expense of approximately $14.0 million will be recognized over the remaining vesting term of approximately 1.9 years.

The assumptions used in the Black-Scholes option-pricing model are as follows:


	Stock Option
	Year Ended December 31,
	2016			2015			2014
Weighted average grant date fair value (per share)	$	24.30		$	71.50		$	142.90
Risk-free interest rate		1.7	%		1.7	%		1.8	%
Expected dividend yield		0.0	%		0.0	%		0.0	%
Expected volatility		57.5	%		64.7	%		76.3	%
Expected term (in years)		5.8			6.0			5.9


	ESPP
	Year Ended December 31,
	2016			2015
Weighted average grant date fair value (per share)	$	17.80		$	45.50
Risk-free interest rate		0.7	%		0.5	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		62.7	%		61.2	%
Expected term (in years)		1.3			1.3

Risk-free Interest Rate. The risk-free interest rate assumption was based on the United States Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued.

Expected Dividend Yield. The expected dividend yield is zero because the Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future.

Expected Volatility. Prior to January 1, 2016, the expected volatility is estimated based on volatilities of a peer group of similar companies whose share prices are publicly available. Since January 1, 2016, the expected volatility is estimated based on a weighted-average volatility of our actual historical volatility since the Company’s initial public offering in November 2013 and the historical stock volatilities of a peer group of similar companies whose share prices are publicly available. The Company continues to use the historical volatility of peer entities due to the lack of sufficient historical data of its stock price since its initial public offering. The peer group consisted of other publicly traded companies in the same industry and in a similar stage of development. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Expected Term. The Company utilized the simplified method for estimating the expected term of stock option grants. Under this approach, the weighted-average expected term is presumed to be the average of the vesting term and the contractual term of the option. The Company estimates the expected term of the ESPP using expected life for each tranche during the two-year offering period.

The Company is also required to estimate forfeitures at the time of grant, and revise those estimates in subsequent periods if actual forfeitures differ from its estimates. Historical data was used to estimate pre-vesting option forfeitures and record stock-based compensation expense only for those awards that are expected to vest.

Common Stock Reserved for Future Issuance

The following shares of common stock are reserved for future issuance at December 31, 2016 (in thousands):


Common stock warrants outstanding			99
Stock options issued and outstanding			822
Authorized for future option grants			56
Employee stock purchase plan			7

			984

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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-Publisher FASB
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+ Details

Commitments and Contingencies

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

8. Commitments and Contingencies

From time to time, the Company may be subject to legal proceedings, regulatory encounters or other matters arising in the ordinary course of business, including actions with respect to intellectual property, employment, product liability, and contractual matters. In connection with these matters, the Company assesses, on a regular basis, the probability and range of possible loss based on the developments in these matters. A liability is recorded in the financial statements if it is determined that it is probable that a loss has been incurred, and that the amount or range of the loss can be reasonably estimated. Because of the uncertainties related to the occurrence, amount, and range of loss on any pending actions, the Company is currently unable to predict their ultimate outcome, and, with respect to any pending litigation or claim where no liability has been accrued, to make a meaningful estimate of the reasonably possible loss or range of loss that could result from an unfavorable outcome. At September 30, 2017 and December 31, 2016, there were no legal proceedings, regulatory encounters or other matters for which the negative outcome was considered probable or for which the amount or range of loss was estimable.

10. Commitments and Contingencies

From time to time, the Company may be subject to legal proceedings or regulatory encounters or other matters arising in the ordinary course of business, including actions with respect to intellectual property, employment, product liability, and contractual matters. In connection with these matters, the Company assesses, on a regular basis, the probability and range of possible loss based on the developments in these matters. A liability is recorded in the financial statements if it is believed to be probable that a loss has been incurred and the amount of the loss can be reasonably estimated. Because of the uncertainties related to the occurrence, amount, and range of loss on any pending actions, the Company is currently unable to predict their ultimate outcome, and, with respect to any pending litigation or claim where no liability has been accrued, to make a meaningful estimate of the reasonably possible loss or range of loss that could result from an unfavorable outcome. At December 31, 2016 and 2015, there were no material matters for which a negative outcome was considered probable or estimable.

Operating leases

Under a noncancelable operating lease agreement, as amended (“Existing Operating Lease”), the Company leases manufacturing, laboratory and office space in San Diego, California. The lease term extends through May 2022. As a lease incentive from the landlord under the Existing Operating Lease, the Company received a tenant improvement allowance (“TI Allowance”) of approximately $0.9 million and $1.6 million, for the years ended December 31, 2015 and 2014, respectively, for nonstructural improvements to the buildings. The Company recorded the incentives as increases to both property and equipment and deferred rent, which are amortized on a straight-line basis over the life of the lease.

In connection with the Existing Operating Lease, the Company has a $0.5 million unsecured standby letter of credit arrangement with a bank under which the landlord of the building is the beneficiary. The expiration of the standby letter of credit is July 14, 2019.

On June 30, 2016, the Company entered into a lease agreement for general office and manufacturing space located on Barnes Canyon Road in San Diego, California (the “Barnes Canyon Lease”). The Barnes Canyon Lease is scheduled to expire in November 2023. The Company will also have a one-time option to extend the term of the lease for a period of not less than 36 months and not greater than 60 months, by delivering notice to the landlord at least nine months and not more than 12 months prior to the expiration of the lease.

The Barnes Canyon Lease allows for a TI Allowance of up to approximately $3.4 million to be applied to non-structural improvements to the building. Any amounts utilized by the Company from the TI Allowance will be subject to an interest accrual at a rate of 8.0% per annum and must be repaid in full during the lease term in monthly installments (the “TI Rent”) concurrently with the base rent. The tenant improvement costs are initially paid by the Company in full and the TI Allowance is subsequently reimbursed by the landlord in the proportion of TI Allowance to the total project budget. During the year ended December 31, 2016, costs incurred for non-structural improvements to the facility were $1.0 million, of which $0.7 million are reimbursable by the landlord. As of December 31, 2016, the Company did not receive any reimbursement from the landlord and recorded a $0.7 million receivable in other current assets on the accompanying balance sheet. The Company retains the right at any time during the lease term to prepay all or any portion of the TI Allowance drawn and outstanding without penalty, in which case the outstanding TI Rent would be reduced to reflect the TI Allowance prepayment and interest would cease to accrue on the prepaid portion of the TI Allowance.

The monthly rent, except TI Rent mentioned above, increases by a fixed percentage each year on the anniversary of the respective rent commencement date of the Existing Operating Lease and Barnes Canyon Lease. The difference between the straight-line expense over the term of the lease and actual amounts paid are recorded as deferred rent. Deferred rent arising from rent escalation provisions and lease incentives totaled $3.7 million at both December 31, 2016 and 2015, respectively. Rent expense for the three years ended December 31, 2016, 2015 and 2014, was $3.1 million, $2.6 million, and $2.1 million, respectively.

Future minimum payments under the aforementioned noncancelable operating leases for each of the five succeeding years following December 31, 2016 are as follows (in thousands):


2017	$	3,198
2018		3,630
2019		1,899
2020		643
2021		662
Thereafter		1,323

	$	11,355

Not included in the table above is the Barnes Canyon Lease TI Rent. No TI Rent was due as of December 31, 2016. Assuming the full TI Allowance is drawn on April 1, 2017, such TI Rent would be $0.5 million for the year ended December 31, 2017, $0.7 million for each of the years ended December 31, 2018 through 2021, and $1.3 million for the years ended December 31, 2022 and thereafter.

Subsequent Event	9 Months Ended	12 Months Ended
Subsequent Event	Sep. 30, 2017	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Event	9. Subsequent Events On October 9, 2017, the Company effected a 1-for-10 reverse stock split of its issued and outstanding shares of common stock. The par value per share and the authorized number of shares of common stock and preferred stock were not adjusted as a result of the reverse stock split. All common stock share and per-share amounts for all periods presented in these condensed financial statements have been adjusted to reflect the reverse stock split. The number of authorized shares of common stock remains at 100 million shares. On October 17, 2017, the Company completed a registered public offering of 4,630,000 shares of its common stock, Series A warrants to purchase up to 4,630,000 shares of its common stock and Series B warrants to purchase up to 4,630,000 shares of its common stock, at a public offering price of $3.50 per share and accompanying warrants. The gross proceeds to the Company from the offering were approximately $16.2 million, before deducting underwriting discounts and commissions and other offering expenses payable by the Company. The Series A warrants have an exercise price of $3.50 per share, are immediately exercisable, and will expire on the 5-year anniversary of the date of issuance. The Series B warrants have an exercise price of $3.50 per share, are immediately exercisable, and will expire on the 6-month anniversary of the date of issuance. As a result of the completion of the financing, the Company has satisfied the equity financing covenant in the Term Loan Agreement, although it remains subject to additional covenants.	12. Subsequent Event On March 7, 2017, the Company entered into the Fourth Amendment, which includes a limited waiver of any event of default that could have occurred due to the inclusion of the explanatory paragraph that describes conditions that raise substantial doubt about our ability to continue as a going concern in the report of the Company’s independent registered public accounting firm contained in the accompanying financial statements, in consideration for which we agreed to: (i) complete an equity financing in which the Company’s gross proceeds from the sale of equity securities is at least $30.0 million, no later than January 15, 2018, (ii) issue Capital Royalty Partners warrants to purchase an aggregate of 193,788 shares of our common stock at an exercise price equal to $23.50 per share, the closing price of our common stock on the NASDAQ Global Market on the date of the Fourth Amendment, (iii) increase our minimum cash balance requirement under the Term Loan Agreement from $2.0 million to $10.0 million, (iv) provide Capital Royalty Partners the same information we make available to our board of directors, subject to limited exceptions, and (v) not incur additional third party indebtedness secured solely by accounts receivable, inventory and cash. In addition, we agreed to increase the Back End Financing Fee to 5.0% of the entire aggregate principal amount of borrowings outstanding, including total PIK Loans issued, under the Term Loan Agreement, which is $81.1 million as of December 31, 2016. The Back End Financing Fee is payable at maturity of our loans and on the principal amount of any loans for which we make an optional prepayment, and may be payable in connection with asset sales not permitted under the Term Loan Agreement or in connection with a change of control. (See Note 5 “Term Loan Agreement”)

Financial Statement Information

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Financial Statement Information

3. Financial Statement Information

Short-term investments


At December 31, 2016	Maturity (in years)		Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper		Less than 1	$	8,483	$	1	$	(2	)	$	8,482

Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants			$	354	$	26	$	(2	)	$	378

Total			$	8,837	$	27	$	(4	)	$	8,860


At December 31, 2015	Maturity (in years)		Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper		Less than 1	$	21,712	$	23	$	—		$	21,735
US Treasuries		Less than 1		2,035		—		(1	)		2,034
Government-sponsored enterprise securities		Less than 1		4,029		—		(2	)		4,027

			$	27,776	$	23	$	(3	)	$	27,796

Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants			$	224	$	1	$	(3	)	$	222

Total			$	28,000	$	24	$	(6	)	$	28,018

Accounts Receivable

Accounts receivable consisted of the following at (in thousands):


	December 31,
	2016			2015
Accounts receivable	$	12,112		$	14,583
Less allowance for doubtful accounts, and product returns		(940	)		(528	)

Total	$	11,172		$	14,055

The following table provides a reconciliation of the change in estimated allowance for doubtful accounts, and product returns for the years ended December 31, 2016, 2015 and 2014 (in thousands):


	Allowance for doubtful accounts
Balance at December 31, 2013	$	218
Provision for doubtful accounts and return reserves		188
Write-offs and adjustments, net of recoveries		(153	)

Balance at December 31, 2014	$	253

Provision for doubtful accounts and return reserves		70
Write-offs and adjustments, net of recoveries		(102	)

Balance at December 31, 2015	$	221

Provision for doubtful accounts and return reserves		632
Write-offs and adjustments, net of recoveries		(118	)

Balance at December 31, 2016	$	735

Inventory

Inventory consisted of the following at (in thousands):


	December 31,
	2016		2015
Raw materials	$	9,375	$	10,606
Work in process		4,395		3,394
Finished goods		7,425		3,543

Total	$	21,195	$	17,543

Property and Equipment

Property and equipment consisted of the following at (in thousands):


	December 31,
	2016			2015
Leasehold improvements	$	8,851		$	7,781
Computer equipment and software		7,844			6,599
Office furniture and equipment		4,185			3,898
Manufacturing and scientific equipment		16,785			12,793

		37,665			31,071
Less accumulated depreciation and amortization		(19,256	)		(15,545	)

Total	$	18,409		$	15,526

Depreciation and amortization expense related to property and equipment amounted to $5.2 million, $4.5 million, and $4.1 million for the years ended December 31, 2016, 2015 and 2014, respectively.

Intangible Assets Subject to Amortization

Intangible assets subject to amortization consist of patents purchased or licensed that are related to the Company’s commercialized products. The following represents the capitalized patents at December 31, 2016 and 2015 (in thousands):


	December 31,
	2016			2015
Gross amount	$	3,247		$	3,247
Accumulated amortization		(1,463	)		(1,137	)

Total	$	1,784		$	2,110

Weighted average remaining amortization period (in months)		66			78

Amortization expense related to intangible assets subject to amortization amounted to $0.3 million for each of the years ended December 31, 2016, 2015 and 2014. The amortization expense is recorded in cost of sales in the statement of operations. The estimated annual amortization is $0.3 million for 2017 and periods thereafter.

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

7. Income Taxes

The provision (benefit) for income taxes reconciles to the amount computed by applying the federal statutory rate to income before taxes as follows (in thousands):


	Year Ended December 31,
	2016			2015			2014
Income tax benefit at federal statutory rate	$	(28,362	)	$	(24,616	)	$	(27,065	)
State income tax, net of federal benefit		(2,393	)		(2,285	)		(3,912	)
Research and development credits		(720	)		(1,796	)		(646	)
Uncertain tax position		—			3,154			—
Stock-based compensation		1,686			1,904			1,973
Other		456			550			355
Removal of net operating losses and research and development credits		—			8,344			—
Change in valuation allowance		29,318			14,755			29,366

Income tax expense (recovery)	$	(15	)	$	10		$	71

Significant components of the Company’s net deferred income tax assets at December 31, 2016 and 2015 are shown below (in thousands). A valuation allowance has been recorded to offset the net deferred tax asset as of December 31, 2016 and 2015, as the realization of such assets does not meet the more-likely-than-not threshold.


	December 31,
	2016			2015
Deferred tax assets:
Net operating loss (NOL) carryforwards	$	100,251		$	79,233
Research and development tax credits carryforwards		2,543			1,832
Capitalized research and development expenses		16,673			13,296
Deferred rent		537			168
Accrued compensation		11,332			9,309
Other		5,931			4,104

Total deferred tax assets		137,267			107,942
Less valuation allowance		(137,267	)		(107,942	)

Net deferred tax assets	$	—		$	—

The California NOL carry forwards will expire as follows (in thousands):


Year ended December 31,
2016	$	624
2017	$	2,052
Thereafter	$	167,828

As of December 31, 2016, the Company has accumulated federal and state NOL carryforwards of approximately $283.5 million and $269.7 million, respectively, not considering the annual limitation of Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”) discussed below. The federal and state tax loss carryforwards begin to expire in 2026 and 2016, respectively, unless previously utilized. The Company also has federal and California research credit carryforwards of approximately $4.1 million and $4.6 million, respectively. The federal research credit carryforwards will begin expiring in 2028 unless previously utilized. The California research credit will carry forward indefinitely. Approximately $1.8 million of the NOL carryforwards relates to excess tax deductions for stock compensation, the income tax benefit of which will be recorded as additional paid-in capital if and when realized.

Utilization of the NOLs and R&D credit carryforwards are subject to annual limitations due to ownership change limitations that have occurred or that could occur in the future, as required by Section 382 of the Code, as well as similar state and foreign provisions. These ownership changes may limit the amount of NOLs and R&D credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change,” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders.

Although the Company determined that it is more likely than not that an ownership change had occurred in March 2015, the Company has not completed a formal update of its Section 382 analysis subsequent to December 31, 2013. Until this analysis has been updated, the Company has removed deferred tax assets for NOLs of $16.0 million and research and development credits of $2.9 million from its deferred tax asset schedule and has recorded a corresponding decrease to its valuation allowance. The amount presented as a deferred tax asset with respect to losses and credits after the removal of potentially limited amounts reflects the estimated asset value using the Section 382 limitation criteria as of the date of the March 2015 public offering of 603,750 shares of common stock, given that it is possible that this transaction may have triggered the limitation. When this analysis is finalized, the Company will reassess the amount of NOLs and credits subject to limitation under Section 382. Due to the existence of the valuation allowance, future changes in the deferred tax assets related to these tax attributes will not impact the Company’s effective tax rate.

The evaluation of uncertainty in a tax position is a two-step process. The first step involves recognition. The Company determines whether it is more likely than not that a tax position will be sustained upon tax examination, including resolution of any related appeals or litigation, based on only the technical merits of the position. The technical merits of a tax position are derived from both statutory and judicial authority (legislation and statutes, legislative intent, regulations, rulings, and case law) and their applicability to the facts and circumstances of the tax position. If a tax position does not meet the more-likely-than-not recognition threshold, the benefit of that position is not recognized in the financial statements. The second step is measurement. A tax position that meets the more-likely-than-not recognition threshold is measured to determine the amount of benefit to recognize in the financial statements. The tax position is measured as the largest amount of benefit that is greater than 50% likely of being realized upon ultimate resolution with a taxing authority.

The following table summarizes the activity related to the Company’s gross unrecognized tax benefits at the beginning and end of the years ended December 31, 2016, 2015 and 2014 (in thousands):


	Year Ended December 31,
	2016			2015		2014
Gross unrecognized tax benefits at the beginning of the year	$	7,594		$	3,539	$	1,912
Increases related to current year positions		580			474		476
Increases (decreases) related to prior year positions		(7	)		3,581		1,151
Expiration of unrecognized tax benefits		—			—		—

Gross unrecognized tax benefits at the end of the year	$	8,167		$	7,594	$	3,539

As of December 31, 2016, the Company has $5.9 million of unrecognized tax benefits that, if recognized and realized would impact the effective tax rate.

The Company’s practice is to recognize interest and penalties related to income tax matters in income tax expense. The Company had no accrual for interest and penalties on the Company’s balance sheets and has not recognized interest and penalties in the statements of operations for the years ended December 31, 2016 and 2015. The Company does not expect any significant increases or decreases to its unrecognized tax benefits within the next 12 months.

The Company is subject to taxation in the United States and state jurisdictions. The Company’s tax years from 2006 (inception) are subject to examination by the United States and state authorities due to the carry forward of unutilized NOLs and research and development credits.

Collaborations	12 Months Ended
Collaborations	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations	8. Collaborations DexCom Development and Commercialization Agreement In February 2012, the Company entered into a Development and Commercialization Agreement (the “DexCom Agreement”) with DexCom, Inc. (“DexCom”) for the purpose of collaborating on the development and commercialization of an integrated system which incorporates the t:slim Insulin Delivery System with DexCom’s proprietary CGM system. Under the DexCom Agreement, the Company paid DexCom $1.0 million at the commencement of the collaboration in 2012, $1.0 million in 2014 upon the achievement of t:slim G4 pre-market approval (“PMA”) submission to the FDA and an additional $1.0 million in September 2015 upon approval of the PMA submission by the FDA. All payments were recorded as research and development costs in their respective years. Additionally, upon commercialization of the t:slim G4 Pump, and as compensation for the non-exclusive license rights, under the original DexCom Agreement, the Company agreed to pay DexCom a royalty calculated at $100 per integrated system sold. In September 2015, the Company entered into an amendment to the DexCom Agreement (the “Amendment”). Pursuant to the Amendment, in lieu of the $100 royalty payment for each integrated system sold, the Company agreed to commit $100 of each t:slim G4 integrated system sold to incremental marketing activities associated with t:slim G4 integrated systems that are in addition to a level of ordinary course marketing activities or marketing activities to support other Company and DexCom jointly funded development projects. The committed marketing fund is recorded as an increase to cost of sales and current liability in the period that the related t:slim G4 Pump sale is recorded. The Company recorded such marketing fund commitment of $0.7 million and $0.4 million in the years ended December 31, 2016 and 2015, respectively. The Company utilized the committed marketing funds of $0.4 million and zero in the years ended December 31, 2016 and 2015, respectively. As of December 31, 2016 and 2015, the Company had a marketing fund liability of $0.7 million and $0.4 million, respectively, recorded in other current liabilities on the accompanying balance sheet. JDRF Collaboration In January 2013, the Company entered into a Research, Development and Commercialization Agreement (“JDRF Agreement”) with JDRF to develop the t:dual Infusion System, a first-of-its-kind, dual-chamber infusion pump for the management of diabetes. According to the terms of the JDRF Agreement, JDRF would provide research funding of up to $3.0 million based on the achievement of research and development milestones, not to exceed research costs incurred by the Company. In February 2016, the Company and JDRF entered into a termination agreement (“JDRF Termination Agreement”), where both parties mutually terminated the JDRF Agreement. As of December 31, 2015, milestone payment achievements totaled $0.7 million, and research and development costs were offset cumulatively by $0.5 million. Under the terms of the JDRF Termination Agreement, the Company agreed to repay JDRF $0.7 million, which is equal to the amount of milestone payments received by the Company to date. The Company accrued for the repayment in other current liabilities on the accompanying balance sheet as of December 31, 2015 and repaid such amount during the first quarter of 2016.

Employee Benefits	12 Months Ended
Employee Benefits	Dec. 31, 2016
Postemployment Benefits [Abstract]
Employee Benefits	9. Employee Benefits Employee 401(k) Plan The Company has a defined contribution 401(k) plan for employees who are at least 18 years of age. Employees are eligible to participate in the plan beginning on the first day of the calendar quarter following their date of hire. Under the terms of the plan, employees may make voluntary contributions as a percent of compensation. The Company does not provide a matching contribution program. Nonqualified Deferred Compensation Plan On June 16, 2014, the Company’s Board of Directors adopted and approved the Tandem Diabetes Care, Inc. Deferred Compensation Plan (the “Plan”). The Plan is a nonqualified deferred compensation program sponsored by the Company to provide its non-employee directors and certain of its management employees designated by the Board (or a committee appointed by the Board to administer the Plan) the opportunity to defer compensation under the Plan. The effective date for the Plan for the first year was July 1, 2014, and thereafter the plan year will be from January 1 to December 31. There is no limit to the amount that a participant may defer under the Plan whether in a particular plan year or in aggregate. At the discretion of the Board (or a committee appointed by the Board to administer the Plan), the Company may make additional contributions to be credited to the account of any or all participants in the Plan. All contributions by the participant, and any contributions that may be made by the Company, will be immediately fully vested. As of December 31, 2016, the Company has not made any contributions. Under the terms of the Plan, the Company has established a Rabbi Trust for the purpose of reserving any benefits that may become payable under the Plan. Distributions from the Plan will be governed by the Code and the terms of the Plan. Company assets designated to pay benefits under the plan are held by a Rabbi Trust and are subject to the general creditors of the Company. The amounts deferred are invested in assets at the direction of the employee. The assets and liabilities of the Rabbi Trust are recorded at fair value and are accounted for as assets and liabilities of the Company. As of December 31, 2016 and 2015, the Company held deferred compensation plan assets of $378,000 and $222,000 in short-term investments on its balance sheets. The assets were invested in mutual funds. The fair market value of the assets held in the Deferred Compensation Plan was based on unadjusted quoted prices in active markets. The Company carried a corresponding deferred compensation liability in other long-term liabilities on its balance sheet of $378,000 and $222,000 as of December 31, 2016 and December 31, 2015, respectively.

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

11. Selected Quarterly Financial Data (Unaudited)

Quarterly financial information for fiscal 2016 and 2015 is presented in the following table, in thousands, except per share data:


	For the Quarter Ending
	March 31			June 30			September 30			December 31
2016:
Revenue	$	20,058		$	22,985		$	12,293		$	28,912
Gross profit	$	6,927		$	8,176		$	(1,577	)	$	10,065
Operating expenses	$	26,166		$	25,229		$	26,837		$	23,411
Operating loss	$	(19,239	)	$	(17,053	)	$	(28,414	)	$	(13,346	)
Net loss	$	(20,485	)	$	(18,326	)	$	(29,815	)	$	(14,822	)
Basic and diluted net loss per share⁽¹⁾	$	(6.80	)	$	(6.00	)	$	(9.70	)	$	(4.80	)
2015:
Revenue	$	12,308		$	15,706		$	15,716		$	29,120
Gross profit	$	2,808		$	4,801		$	5,513		$	13,458
Operating expenses	$	23,218		$	23,472		$	24,216		$	24,679
Operating loss	$	(20,410	)	$	(18,671	)	$	(18,703	)	$	(11,221	)
Net loss	$	(21,208	)	$	(19,533	)	$	(19,585	)	$	(12,093	)
Basic and diluted net loss per share⁽¹⁾	$	(8.30	)	$	(6.50	)	$	(6.50	)	$	(4.00	)
2014:
Revenue	$	8,066		$	10,254		$	13,513		$	17,889
Gross profit	$	867		$	3,448		$	4,396		$	6,537
Operating expenses	$	21,704		$	21,766		$	23,403		$	24,039
Operating loss	$	(20,837	)	$	(18,318	)	$	(19,007	)	$	(17,502	)
Net loss	$	(21,961	)	$	(19,197	)	$	(19,901	)	$	(18,465	)
Basic and diluted net loss per share⁽¹⁾	$	(9.60	)	$	(8.30	)	$	(8.50	)	$	(7.80	)

⁽¹⁾	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

Organization and Basis of Presentation (Policies)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Accounting Policies [Abstract]

The Company

The Company

•

the t:flex Insulin Delivery System, or t:flex, for people with greater insulin needs.

The Company

•

the t:slim Insulin Delivery System, or t:slim,

•

the t:flex Insulin Delivery System, or t:flex,

•

the t:slim G4 Insulin Delivery System, or t:slim G4, and

•

the t:slim X2 Insulin Delivery System, or t:slim X2.

On October 9, 2017, the Company effected a 1-for-10 reverse stock split of its issued and outstanding shares of common stock. The par value per share and the authorized number of shares of common stock and preferred stock were not adjusted as a result of the reverse stock split. All common stock share and per-share amounts for all periods presented in these financial statements have been adjusted to reflect the reverse stock split. The number of authorized shares of common stock remains at 100 million shares.

Basis of Presentation

Basis of Presentation

Basis of Presentation

Use of Estimates

Use of Estimates

Use of Estimates

Restricted Cash

Restricted Cash

Restricted Cash

Restricted cash as of December 31, 2016 and 2015 was comprised of a $2.0 million minimum cash balance requirement in connection with the Term Loan Agreement (see Note 5, “Term Loan Agreement”).

Accounts Receivable

Accounts Receivable

Accounts Receivable

The Company grants credit to various customers in the normal course of business. The Company maintains an allowance for doubtful accounts for potential credit losses. Provisions are made based on historical experience, assessment of specific risk, specific review of outstanding invoices or various assumptions and estimates that are believed to be reasonable under the circumstances. Uncollectible accounts are written off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a balance is uncollectible.

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Revenue Recognition

Revenue Recognition

Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred and title passed, the price is fixed or determinable, and collectability is reasonably assured.

Trade-In Rights

Revenue Recognition for Arrangements with Multiple Deliverables

Product Returns

Revenue Recognition

Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred and title passed, the price is fixed or determinable, and collectability is reasonably assured.

Trade-In Rights

Revenue Recognition for Arrangements with Multiple Deliverables

The Company considers the deliverables in its product offering as separate units of accounting and recognizes deliverables as revenue upon delivery only if (i) the deliverable has standalone value and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is probable and substantially controlled by the Company. The Company allocates consideration to the separate units of accounting, unless the undelivered elements were deemed perfunctory and inconsequential. The amount of the determined guarantee fair value is allocated in full to the guarantee and the remaining allocable consideration is allocated to other separate units of accounting using the relative selling price method, in which allocation of consideration is based on vendor-specific objective evidence (“VSOE”) if available, third-party evidence (“TPE”), or if VSOE and TPE are not available, management’s best estimate of a standalone selling price (“ESP”) for the undelivered elements.

The Company offers a cloud-based data management application, t:connect, which is made available to customers upon purchase of any of its insulin pumps. In July 2016, the Company received clearance from the FDA to begin offering the Tandem Device Updater, a Mac and PC-compatible tool for the remote update of Tandem insulin pump software. Utilizing Tandem Device Updater, the Company may from time to time provide future unspecified software upgrades to the insulin pump’s essential software. The t:connect service and the embedded right included with qualifying insulin pumps to receive, on a when-and-if-available basis, future unspecified software upgrades relating to the product’s essential software are deemed undelivered elements at the time of the insulin pump sale. Because the Company has neither VSOE nor TPE for these deliverables, the allocation of revenue is based on the Company’s ESP. The Company establishes its ESP based on the estimated cost to provide such services, including consideration for a reasonable profit margin, which is then corroborated by comparable market data. The Company allocates fair value based on management’s ESP to these elements at the time of sale and recognizes the revenue over a four-year period, which is the hosting period for t:connect and the period that software upgrades are expected to be provided. At December 31, 2016 and 2015, $1.6 million and $1.1 million were recorded as deferred revenue for these undelivered elements, respectively. All other undelivered elements at the time of sale are deemed inconsequential or perfunctory.

Product Returns

The Company offers a 30-day right of return to its customers from the date of shipment of any of its insulin pumps, provided a physician’s confirmation of the medical reason for the return is received. Estimated allowances for sales returns are based on historical returned quantities as compared to pump shipments in those same periods of return. The return rate is then applied to the sales of the current period to establish a reserve at the end of the period. The return rates used in the reserve are adjusted for known or expected changes in the marketplace when appropriate. The allowance for product returns is recorded as a reduction of revenue and accounts receivable in the period in which the related sale is recorded. The amount recorded on the Company’s balance sheet for product return allowance was $0.2 million and $0.3 million at December 31, 2016 and 2015, respectively. Actual product returns have not differed materially from estimated amounts reserved in the accompanying financial statements.

Warranty Reserve

Warranty Reserve


Balance at December 31, 2016	$	5,690
Provision for warranties issued during the period		4,110
Settlements made during the period		(5,240	)
Increases in warranty estimates		190

Balance at September 30, 2017	$	4,750


Current portion	$	2,080
Non-current portion		2,670

Total	$	4,750

Warranty Reserve

The Company generally provides a four-year warranty on its insulin pumps to end user customers and may replace any pumps that do not function in accordance with the product specifications. Insulin pumps returned to the Company may be refurbished and redeployed. Additionally, the Company offers a six-month warranty on disposable cartridges and infusion sets. Estimated warranty costs are recorded at the time of shipment. Warranty costs are estimated based on the current expected replacement product cost and expected replacement rates based on historical experience. The Company evaluates the reserve quarterly and makes adjustments when appropriate. Changes to the actual replacement rates and actual replacement product costs could have a material impact on the Company’s estimated liability.


	December 31,
(in thousands)	2016			2015
Balance at beginning of the year	$	3,547		$	1,974
Provision for warranties issued during the period		8,830			1,948
Settlements made during the period		(8,739	)		(4,373	)
Increases in warranty estimates		2,052			3,998

Balance at end of the year	$	5,690		$	3,547

Current portion	$	2,302		$	1,050
Non-current portion	$	3,388			2,497

Total	$	5,690		$	3,547

Stock-Based Compensation

Stock-Based Compensation

Stock-Based Compensation

Stock-based compensation cost is measured at the grant date based on the estimated fair value of the award, and the portion that is ultimately expected to vest is recognized as compensation expense over the requisite service period on a straight-line basis. The Company estimates the fair value of stock options issued under the Company’s 2013 Stock Incentive Plan (“2013 Plan”) and shares issued under the Company’s 2013 Employee Stock Purchase Plan (“ESPP”) using a Black-Scholes option-pricing model on the date of grant. The Black-Scholes option-pricing model requires the use of subjective assumptions including volatility, expected term, and risk-free rate. For awards that vest based on service conditions, the Company recognizes expense using the straight-line method less estimated forfeitures based on historical experience.

Net Loss Per Share

Net Loss Per Share


	Nine Months Ended September 30,
	2017		2016
Common stock warrants		—		99
Common stock options		3		262
ESPP		—		7

		3		368

Net Loss Per Share


	Year Ended December 31,
	2016		2015		2014
Warrants for common stock		—		99		100
Common stock options		151		201		223
ESPP		2		0		0

		153		3,00		323

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Recent Accounting Pronouncements

In August 2016, the Financial Accounting Standards Board (“FASB”) issued new guidance that clarifies how entities should classify certain cash receipts and cash payments on the statement of cash flows. The guidance also clarifies how the predominance principle should be applied when cash receipts and cash payments have aspects of more than one class of cash flows. The guidance is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those years. The Company does not believe the adoption of the standard will have a material impact on the Company’s statement of cash flow.

In March 2016, FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718) (“ASU 2016-09”), which is intended to simplify several areas of accounting for share-based payment arrangements. The amendments in this update cover such areas as the recognition of excess tax benefits and deficiencies, the classification of those excess benefits on the statement of cash flows, an accounting policy election for forfeitures, the amount an employer can withhold to cover income taxes and still qualify for equity classification and the classification of those taxes paid on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods. The Company will adopt this standard beginning in the first quarter of 2017. The Company has excess tax benefits for which a benefit could not previously be recognized of approximately $656,000. Upon adoption, the balance of the unrecognized excess tax benefits will be reversed with the impact recorded to (accumulated deficit) retained earnings, including any change to the valuation allowance as a result of the adoption. Due to the full valuation allowance on the U.S. deferred tax assets as of December 31, 2016, the Company does not expect any impact to the financial statements as a result of this adoption in the first quarter of 2017.

In February 2016, FASB issued final guidance for lease accounting. The new guidance requires lessees to put most leases on their balance sheet but to recognize expenses on their income statement in a manner similar to today’s accounting. The new guidance also eliminates today’s real estate-specific provisions for all entities. The standard is effective for public business entities for annual periods beginning after December 15, 2018, and interim periods within those years. Early adoption is permitted for all entities. The Company is in the process of assessing the impact of the adoption of the standard on its financial statements.

Segment Reporting

Segment Reporting

Cash and Cash Equivalents

Cash and Cash Equivalents

Short Term Investments

Short-Term Investments

Concentration of Credit Risk

Concentration of Credit Risk

The following table summarizes customers who accounted for 10% or more of net accounts receivable:


	December 31,
	2016			2015
Edgepark Medical Supplies, Inc.		15.2	%		16.4	%
Byram Healthcare		14.7	%		21.8	%

The following table summarizes customers who accounted for 10% or more of sales for the periods presented:


	December 31,
	2016			2015			2014
Edgepark Medical Supplies, Inc.		18.7	%		17.8	%		16.0	%
Byram Healthcare		14.0	%		17.2	%		10.9	%
Solara Medical Supplies, Inc.		10.7	%		N/A			N/A
CCS Medical		N/A			N/A			11.6	%

Inventories

Inventories

Long Lived Assets

Long Lived Assets

Property and Equipment

Patents

Deferred Rent

Deferred Rent

Research and Development Costs

Research and Development Costs

Income Taxes

Income Taxes

Advertising Costs

Advertising Costs

The Company expenses advertising costs as they are incurred. For the years ended December 31, 2016, 2015 and 2014, advertising costs were $0.9 million, $1.0 million, and $1.5 million, respectively.

Shipping and Handling Expenses

Shipping and Handling Expenses

Shipping and handling expenses associated with product delivery are included within cost of sales in the Company’s statements of operations.

Comprehensive Loss

Comprehensive Loss

Reclassifications

Reclassifications

Certain reclassifications of prior year amounts have been made to conform to the current year presentation.

Summary of Significant Accounting Policies (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Accounting Policies [Abstract]

Summary of Reconciliation of Change in Product Warranty Liabilities


Balance at December 31, 2016	$	5,690
Provision for warranties issued during the period		4,110
Settlements made during the period		(5,240	)
Increases in warranty estimates		190

Balance at September 30, 2017	$	4,750


Current portion	$	2,080
Non-current portion		2,670

Total	$	4,750

The following table provides a reconciliation of the change in estimated warranty liabilities for the years ended December 31, 2016 and 2015:


	December 31,
(in thousands)	2016			2015
Balance at beginning of the year	$	3,547		$	1,974
Provision for warranties issued during the period		8,830			1,948
Settlements made during the period		(8,739	)		(4,373	)
Increases in warranty estimates		2,052			3,998

Balance at end of the year	$	5,690		$	3,547

Current portion	$	2,302		$	1,050
Non-current portion	$	3,388			2,497

Total	$	5,690		$	3,547

Schedule of Anti-Dilutive Securities


	Nine Months Ended September 30,
	2017		2016
Common stock warrants		—		99
Common stock options		3		262
ESPP		—		7

		3		368

Net Loss Per Share


	Year Ended December 31,
	2016		2015		2014
Warrants for common stock		—		99		100
Common stock options		151		201		223
ESPP		2		0		0

		153		3,00		323

Summary of Customers Accounted for 10% or More

The following table summarizes customers who accounted for 10% or more of net accounts receivable:


	December 31,
	2016			2015
Edgepark Medical Supplies, Inc.		15.2	%		16.4	%
Byram Healthcare		14.7	%		21.8	%

The following table summarizes customers who accounted for 10% or more of sales for the periods presented:


	December 31,
	2016			2015			2014
Edgepark Medical Supplies, Inc.		18.7	%		17.8	%		16.0	%
Byram Healthcare		14.0	%		17.2	%		10.9	%
Solara Medical Supplies, Inc.		10.7	%		N/A			N/A
CCS Medical		N/A			N/A			11.6	%

Short-Term Investments (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Summary of Estimated Fair Value of Short-Term Investments


At September 30, 2017	Maturity (in years)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants		$	416	$	43	$	—	$	459

Total		$	416	$	43	$	—	$	459


At December 31, 2016	Maturity (in years)		Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper		Less than 1	$	8,483	$	1	$	(2	)	$	8,482
Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants			$	354	$	26	$	(2	)	$	378

Total			$	8,837	$	27	$	(4	)	$	8,860


At December 31, 2016	Maturity (in years)		Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper		Less than 1	$	8,483	$	1	$	(2	)	$	8,482

Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants			$	354	$	26	$	(2	)	$	378

Total			$	8,837	$	27	$	(4	)	$	8,860


At December 31, 2015	Maturity (in years)		Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper		Less than 1	$	21,712	$	23	$	—		$	21,735
US Treasuries		Less than 1		2,035		—		(1	)		2,034
Government-sponsored enterprise securities		Less than 1		4,029		—		(2	)		4,027

			$	27,776	$	23	$	(3	)	$	27,796

Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants			$	224	$	1	$	(3	)	$	222

Total			$	28,000	$	24	$	(6	)	$	28,018

Inventory (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Inventory Disclosure [Abstract]

Summary of Inventory

Inventory consisted of the following at September 30, 2017 and December 31, 2016 (in thousands):


	September 30, 2017		December 31, 2016
Raw materials	$	10,138	$	9,375
Work in process		5,497		4,395
Finished goods		14,350		7,425

Total	$	29,985	$	21,195

Inventory consisted of the following at (in thousands):


	December 31,
	2016		2015
Raw materials	$	9,375	$	10,606
Work in process		4,395		3,394
Finished goods		7,425		3,543

Total	$	21,195	$	17,543

Fair Value Measurements (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis


			Fair Value Measurements at September 30, 2017
			(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents⁽¹⁾	$	16,527	$	16,527	$	—	$	—
Mutual funds held for nonqualified deferred compensation plan participants⁽²⁾		459		459		—		—

Total assets	$	16,986	$	16,986	$	—	$	—

Liabilities
Deferred compensation⁽²⁾	$	459	$	459	$	—	$	—

Total liabilities	$	459	$	459	$	—	$	—


			Fair Value Measurements at December 31, 2016
			(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents⁽¹⁾	$	39,941	$	39,941	$	—	$	—
Commercial paper		8,482		—		8,482		—
Mutual funds held for nonqualified deferred compensation plan participants⁽²⁾		378		378		—		—

Total assets	$	48,801	$	40,319	$	8,482	$	—

Liabilities
Deferred compensation⁽²⁾	$	378	$	378	$	—	$	—

Total liabilities	$	378	$	378	$	—	$	—

⁽¹⁾

⁽²⁾


			Fair Value Measurements at December 31, 2016
	December 31, 2016		Level 1		Level 2		Level 3
Assets
Cash equivalents⁽¹⁾	$	39,941	$	39,941	$	—	$	—
Commercial paper		8,482		—		8,482		—
Mutual funds held for nonqualified deferred compensation plan participants⁽²⁾		378		378		—		—

Total assets	$	48,801	$	40,319	$	8,482	$	—

Liabilities
Deferred compensation⁽²⁾	$	378	$	378	$	—	$	—

Total liabilities	$	378	$	378	$	—	$	—


			Fair Value Measurements at December 31, 2015
	December 31, 2015		Level 1		Level 2		Level 3
Assets
Cash equivalents⁽¹⁾	$	23,402	$	23,402	$	—	$	—
Commercial paper		21,735		—		21,735		—
Mutual funds held for nonqualified deferred compensation plan participants⁽²⁾		222		222		—		—
Treasury securities		2,034		2,034		—		—
Government-sponsored enterprise securities		4,027		—		4,027		—

Total assets	$	51,420	$	25,658	$	25,762	$	—

Liabilities
Deferred compensation⁽²⁾	$	222	$	222	$	—	$	—

Total liabilities	$	222	$	222	$	—	$	—

⁽¹⁾	Cash equivalents included money market funds and commercial paper with a maturity of three months or less from the date of purchase.

⁽²⁾

Stockholders' Equity (Deficit) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Equity [Abstract]

Schedule of Shares of Common Stock Reserved for Future Issuance

The following shares of the Company’s common stock were reserved for future issuance at September 30, 2017 (in thousands):


Shares underlying outstanding warrants			293
Shares underlying outstanding stock options			933
Shares authorized for future equity award grants			39
Shares authorized for issuance as ESPP awards			—

			1,265

The following shares of common stock are reserved for future issuance at December 31, 2016 (in thousands):


Common stock warrants outstanding			99
Stock options issued and outstanding			822
Authorized for future option grants			56
Employee stock purchase plan			7

			984

Schedule of Assumptions Used in Black-Scholes Option-Pricing Model

The assumptions used in the Black-Scholes option-pricing model are as follows:


	Stock Options
	Nine Months Ended September 30,
	2017			2016
Weighted average grant date fair value (per share)	$	5.10		$	37.80
Risk-free interest rate		1.9	%		1.4	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		60.0	%		55.5	%
Expected term (in years)		6.1			6.1


	ESPP
	Nine Months Ended September 30,
	2017⁽¹⁾		2016
Weighted average grant date fair value (per share)		N/A	$	26.90
Risk-free interest rate		N/A		0.6	%
Expected dividend yield		N/A		0.0	%
Expected volatility		N/A		56.9	%
Expected term (in years)		N/A		1.3

⁽¹⁾	There were no grants made pursuant to the ESPP during the nine months ended September 30, 2017.

The assumptions used in the Black-Scholes option-pricing model are as follows:


	Stock Option
	Year Ended December 31,
	2016			2015			2014
Weighted average grant date fair value (per share)	$	24.30		$	71.50		$	142.90
Risk-free interest rate		1.7	%		1.7	%		1.8	%
Expected dividend yield		0.0	%		0.0	%		0.0	%
Expected volatility		57.5	%		64.7	%		76.3	%
Expected term (in years)		5.8			6.0			5.9


	ESPP
	Year Ended December 31,
	2016			2015
Weighted average grant date fair value (per share)	$	17.80		$	45.50
Risk-free interest rate		0.7	%		0.5	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		62.7	%		61.2	%
Expected term (in years)		1.3			1.3

Summary for Allocation of Stock-Based Compensation Expense

The following table summarizes the allocation of stock-based compensation expense (in thousands):


	Nine Months Ended September 30,
	2017		2016
Cost of sales	$	1,022	$	776
Selling, general & administrative		8,423		6,992
Research and development		1,057		965

Total	$	10,502	$	8,733

The compensation cost that has been included in the statement of operations for all stock-based compensation arrangements was as follows (in thousands):


	Year Ended December 31,
	2016		2015		2014
Cost of sales	$	1,016	$	1,162	$	1,317
Selling, general & administrative		9,360		10,517		11,886
Research and development		1,284		1,417		1,792

Total	$	11,660	$	13,096	$	14,995

Summary of Stock Option Activities for 2006 Plan and 2013 Plan

The following table summarizes stock option activities for the 2006 Plan and 2013 Plan:


	Total Options			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2014		501,106		$	102.04		8.62	$	23,534
Granted		117,557		$	120.06
Exercised		(24,355	)	$	13.82			$	2,540
Canceled/forfeited/expired		(19,408	)	$	168.63

Outstanding at December 31, 2015		574,900		$	107.22		7.99	$	19,158

Granted		316,671		$	45.75
Exercised		(14,876	)	$	11.49			$	1,049
Canceled/forfeited/expired		(53,857	)	$	126.19

Outstanding at December 31, 2016		822,838		$	84.05		7.92	$	1,593

Vested and expected to vest at December 31, 2016		812,862		$	84.24		7.91	$	1,592
Exercisable at December 31, 2016		423,810		$	98.61		6.80	$	1,554

Financial Statement Information (Tables)

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Accounts Receivable

Accounts receivable consisted of the following at (in thousands):


	December 31,
	2016			2015
Accounts receivable	$	12,112		$	14,583
Less allowance for doubtful accounts, and product returns		(940	)		(528	)

Total	$	11,172		$	14,055

Reconciliation of Change in Estimated Allowance for Doubtful Accounts, and Product Returns

The following table provides a reconciliation of the change in estimated allowance for doubtful accounts, and product returns for the years ended December 31, 2016, 2015 and 2014 (in thousands):


	Allowance for doubtful accounts
Balance at December 31, 2013	$	218
Provision for doubtful accounts and return reserves		188
Write-offs and adjustments, net of recoveries		(153	)

Balance at December 31, 2014	$	253

Provision for doubtful accounts and return reserves		70
Write-offs and adjustments, net of recoveries		(102	)

Balance at December 31, 2015	$	221

Provision for doubtful accounts and return reserves		632
Write-offs and adjustments, net of recoveries		(118	)

Balance at December 31, 2016	$	735

Summary of Property and Equipment

Property and equipment consisted of the following at (in thousands):


	December 31,
	2016			2015
Leasehold improvements	$	8,851		$	7,781
Computer equipment and software		7,844			6,599
Office furniture and equipment		4,185			3,898
Manufacturing and scientific equipment		16,785			12,793

		37,665			31,071
Less accumulated depreciation and amortization		(19,256	)		(15,545	)

Total	$	18,409		$	15,526

Summary of Capitalized Patents

The following represents the capitalized patents at December 31, 2016 and 2015 (in thousands):


	December 31,
	2016			2015
Gross amount	$	3,247		$	3,247
Accumulated amortization		(1,463	)		(1,137	)

Total	$	1,784		$	2,110

Weighted average remaining amortization period (in months)		66			78

Term Loan Agreement (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Future Minimum Principal Payments Under Term Loan Agreement

Future minimum principal payments under the Term Loan Agreement as of December 31, 2016, are as follows (in thousands):


Year ended December 31,
2017	$	—
2018		—
2019		—
2020		81,080
2021		—
Thereafter		—

Total	$	81,080
Less current portion of notes payable		—

Notes payable, net of current portion	$	81,080

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

The provision (benefit) for income taxes reconciles to the amount computed by applying the federal statutory rate to income before taxes as follows (in thousands):


	Year Ended December 31,
	2016			2015			2014
Income tax benefit at federal statutory rate	$	(28,362	)	$	(24,616	)	$	(27,065	)
State income tax, net of federal benefit		(2,393	)		(2,285	)		(3,912	)
Research and development credits		(720	)		(1,796	)		(646	)
Uncertain tax position		—			3,154			—
Stock-based compensation		1,686			1,904			1,973
Other		456			550			355
Removal of net operating losses and research and development credits		—			8,344			—
Change in valuation allowance		29,318			14,755			29,366

Income tax expense (recovery)	$	(15	)	$	10		$	71

Schedule of Deferred Tax Assets and Liabilities


	December 31,
	2016			2015
Deferred tax assets:
Net operating loss (NOL) carryforwards	$	100,251		$	79,233
Research and development tax credits carryforwards		2,543			1,832
Capitalized research and development expenses		16,673			13,296
Deferred rent		537			168
Accrued compensation		11,332			9,309
Other		5,931			4,104

Total deferred tax assets		137,267			107,942
Less valuation allowance		(137,267	)		(107,942	)

Net deferred tax assets	$	—		$	—

California NOL Carry Forwards Expiration

The California NOL carry forwards will expire as follows (in thousands):


Year ended December 31,
2016	$	624
2017	$	2,052
Thereafter	$	167,828

Schedule of Unrecognized Tax Benefits

The following table summarizes the activity related to the Company’s gross unrecognized tax benefits at the beginning and end of the years ended December 31, 2016, 2015 and 2014 (in thousands):


	Year Ended December 31,
	2016			2015		2014
Gross unrecognized tax benefits at the beginning of the year	$	7,594		$	3,539	$	1,912
Increases related to current year positions		580			474		476
Increases (decreases) related to prior year positions		(7	)		3,581		1,151
Expiration of unrecognized tax benefits		—			—		—

Gross unrecognized tax benefits at the end of the year	$	8,167		$	7,594	$	3,539

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Payments Under Noncancelable Operating Leases

Future minimum payments under the aforementioned noncancelable operating leases for each of the five succeeding years following December 31, 2016 are as follows (in thousands):


2017	$	3,198
2018		3,630
2019		1,899
2020		643
2021		662
Thereafter		1,323

	$	11,355

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

Quarterly financial information for fiscal 2016 and 2015 is presented in the following table, in thousands, except per share data:


	For the Quarter Ending
	March 31			June 30			September 30			December 31
2016:
Revenue	$	20,058		$	22,985		$	12,293		$	28,912
Gross profit	$	6,927		$	8,176		$	(1,577	)	$	10,065
Operating expenses	$	26,166		$	25,229		$	26,837		$	23,411
Operating loss	$	(19,239	)	$	(17,053	)	$	(28,414	)	$	(13,346	)
Net loss	$	(20,485	)	$	(18,326	)	$	(29,815	)	$	(14,822	)
Basic and diluted net loss per share⁽¹⁾	$	(6.80	)	$	(6.00	)	$	(9.70	)	$	(4.80	)
2015:
Revenue	$	12,308		$	15,706		$	15,716		$	29,120
Gross profit	$	2,808		$	4,801		$	5,513		$	13,458
Operating expenses	$	23,218		$	23,472		$	24,216		$	24,679
Operating loss	$	(20,410	)	$	(18,671	)	$	(18,703	)	$	(11,221	)
Net loss	$	(21,208	)	$	(19,533	)	$	(19,585	)	$	(12,093	)
Basic and diluted net loss per share⁽¹⁾	$	(8.30	)	$	(6.50	)	$	(6.50	)	$	(4.00	)
2014:
Revenue	$	8,066		$	10,254		$	13,513		$	17,889
Gross profit	$	867		$	3,448		$	4,396		$	6,537
Operating expenses	$	21,704		$	21,766		$	23,403		$	24,039
Operating loss	$	(20,837	)	$	(18,318	)	$	(19,007	)	$	(17,502	)
Net loss	$	(21,961	)	$	(19,197	)	$	(19,901	)	$	(18,465	)
Basic and diluted net loss per share⁽¹⁾	$	(9.60	)	$	(8.30	)	$	(8.50	)	$	(7.80	)

⁽¹⁾	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

Organization and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended													9 Months Ended		12 Months Ended
	Oct. 17, 2017 USD ($) $ / shares shares	Oct. 09, 2017 shares	Mar. 31, 2015 $ / shares shares	Mar. 31, 2017 $ / shares shares	Dec. 31, 2016 USD ($) shares	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) shares	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2017 USD ($) shares	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($)
Organization And Basis Of Presentation [Line Items]
Operating losses and accumulated deficit					$ (404,580)				$ (321,133)								$ (466,207)		$ (404,580)	$ (321,133)
Net loss					(14,822)	$ (29,815)	$ (18,326)	$ (20,485)	$ (12,093)	$ (19,585)	$ (19,533)	$ (21,208)	$ (18,465)	$ (19,901)	$ (19,197)	$ (21,961)	(61,627)	$ (68,624)	(83,447)	(72,418)	$ (79,524)
Cash used from operations																	(54,495)	$ (47,591)	(61,173)	$ (58,764)	$ (61,378)
Cash and cash equivalents and short-term investments including restricted cash-long-term					$ 53,500												22,500		$ 53,500
Restricted cash																	$ 10,000
Number of authorized shares of common stock remains \| shares					100,000,000				100,000,000								100,000,000		100,000,000	100,000,000
Shares offered for public offering \| shares			603,750
Secondary Public Offering [Member]
Organization And Basis Of Presentation [Line Items]
Shares offered for public offering \| shares				1,850,000								603,750
Shares offering price per share \| $ / shares			$ 115.00	$ 12.50								$ 115.00
Subsequent Event [Member]
Organization And Basis Of Presentation [Line Items]
Reverse stock split of company's issued and outstanding shares of common stock description		1-for-10 reverse stock split
Reverse stock split, conversion ratio		0.1
Number of authorized shares of common stock remains \| shares		100,000,000
Subsequent Event [Member] \| Secondary Public Offering [Member]
Organization And Basis Of Presentation [Line Items]
Proceeds from issuance of common stock, gross	$ 16,200
Shares offered for public offering \| shares	4,630,000
Shares offering price per share \| $ / shares	$ 3.50
Expected gross proceeds upon exercise of warrants	$ 16,200
Subsequent Event [Member] \| Series A warrants [Member] \| Secondary Public Offering [Member]
Organization And Basis Of Presentation [Line Items]
Warrants issue to purchase common stock \| shares	4,630,000
Warrants exercise price \| $ / shares	$ 3.50
Public offering period	5 years
Subsequent Event [Member] \| Series B warrants [Member] \| Secondary Public Offering [Member]
Organization And Basis Of Presentation [Line Items]
Warrants issue to purchase common stock \| shares	4,630,000
Warrants exercise price \| $ / shares	$ 3.50
Public offering period	6 months
Term Loan Agreement [Member]
Organization And Basis Of Presentation [Line Items]
Restricted cash																	$ 10,000

Summary of Significant Accounting Policies - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($) Segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		$ 2,000,000	$ 2,000,000
Guarantee liabilities recognized as sales	$ 1,100,000
Guarantee liabilities in other current liabilities	0	$ 1,200,000
Amount for upgradation requested but not yet fulfilled.	$ 200,000
Offered period for sales return	30 days	30 days
Allowance for product returns	$ 200,000	$ 200,000	300,000
Warranty reserve	$ 4,750,000	5,690,000	3,547,000	$ 1,974,000
Excess tax benefits for which benefit could not previously be recognized		$ 8,167,000	7,594,000	3,539,000	$ 1,912,000
Percentage of revenue recognition from contracts with customers	99.00%
Number of operating segments \| Segment		1
Investment held-to-maturity		$ 0	$ 0
Company amortizes patent costs over their estimated useful life		66 months	78 months
Advertising cost		$ 900,000	$ 1,000,000	$ 1,500,000
Debt issuance cost			400,000
ASU 2016-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Excess tax benefits for which benefit could not previously be recognized		656,000
Warranty reserves [Member]
Summary Of Significant Accounting Policies [Line Items]
Warranty reserve	$ 4,800,000	5,700,000	3,500,000
Connect Hosting Service [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue	$ 1,800,000	$ 1,600,000	1,100,000
Revenue recognition hosting period	4 years	4 years
Tandem Pump [Member]
Summary Of Significant Accounting Policies [Line Items]
Warranty period offered	4 years	4 years
Slim cartridges and infusion sets [Member]
Summary Of Significant Accounting Policies [Line Items]
Warranty period offered	6 months	6 months
Trade-in rights reserve [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue		$ 3,200,000
Term Loan Agreement [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 10,000,000	$ 2,000,000	$ 2,000,000
Patents [Member]
Summary Of Significant Accounting Policies [Line Items]
Company amortizes patent costs over their estimated useful life		10 years
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		7 years

Summary of Significant Accounting Policies - Summary of Reconciliation of Change in Product Warranty Liabilities (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement In Standard And Extended Product Warranty Increase Decrease Roll Forward
Beginning balance	$ 5,690	$ 3,547	$ 1,974
Provision for warranties issued during the period	4,110	8,830	1,948
Settlements made during the period	(5,240)	(8,739)	(4,373)
Increases in warranty estimates	190	2,052	3,998
Ending balance	4,750	5,690	3,547
Current portion	2,080	2,302	1,050
Non-current portion	$ 2,670	$ 3,388	$ 2,497

Summary of Significant Accounting Policies - Schedule of Anti-Dilutive Securities (Detail) - shares shares in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3	368	153	300	323
Common stock warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount		99		99	100
Employee Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3	262	151	201	223
ESPP [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount		7	2	0	0

Short-Term Investments - Summary of Estimated Fair Value of Short-Term Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017
Cash Cash Equivalents And Short Term Investments [Line Items]
Short-term investments, Amortized Cost	$ 8,837	$ 28,000	$ 416
Short-term investments, Unrealized Gain	27	24	43
Short-term investments, Unrealized Loss	(4)	(6)
Short-term investments, Estimated Fair Value	8,860	28,018	459
Trading securities - mutual funds held for nonqualified deferred compensation plan participants [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Trading securities, Amortized Cost	354	224	416
Trading securities, Unrealized Gain	26	1	43
Trading securities, Unrealized Loss	(2)	(3)
Trading securities, Estimated Fair Value	378	222	$ 459
Commercial paper [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale investment securities, Amortized Cost	8,483	21,712
Available-for-sale investment securities, Unrealized Gain	1	23
Available-for-sale investment securities, Unrealized Loss	(2)
Available-for-sale investment securities, Estimated Fair Value	$ 8,482	$ 21,735
Commercial paper [Member] \| Maximum [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale investment securities, Maturity (in years)	1 year	1 year
US Treasuries [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale investment securities, Amortized Cost		$ 2,035
Available-for-sale investment securities, Unrealized Loss		(1)
Available-for-sale investment securities, Estimated Fair Value		$ 2,034
US Treasuries [Member] \| Maximum [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale investment securities, Maturity (in years)		1 year
Government-sponsored enterprise securities [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale investment securities, Amortized Cost		$ 4,029
Available-for-sale investment securities, Unrealized Loss		(2)
Available-for-sale investment securities, Estimated Fair Value		$ 4,027
Government-sponsored enterprise securities [Member] \| Maximum [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale investment securities, Maturity (in years)		1 year

Inventory - Summary of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 10,138	$ 9,375	$ 10,606
Work in process	5,497	4,395	3,394
Finished goods	14,350	7,425	3,543
Total	$ 29,985	$ 21,195	$ 17,543

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	$ 16,986	$ 48,801	$ 51,420
Total liabilities	459	378	222
Cash equivalents [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	16,527	39,941	23,402
Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets		8,482	21,735
Mutual funds held for nonqualified deferred compensation plan participants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	459	378	222
US Treasuries [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets			2,034
Government-sponsored enterprise securities [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets			4,027
Deferred compensation [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total liabilities	459	378	222
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	16,986	40,319	25,658
Total liabilities	459	378	222
Level 1 [Member] \| Cash equivalents [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	16,527	39,941	23,402
Level 1 [Member] \| Mutual funds held for nonqualified deferred compensation plan participants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	459	378	222
Level 1 [Member] \| US Treasuries [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets			2,034
Level 1 [Member] \| Deferred compensation [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total liabilities	$ 459	378	222
Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets		8,482	25,762
Level 2 [Member] \| Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets		$ 8,482	21,735
Level 2 [Member] \| Government-sponsored enterprise securities [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets			$ 4,027

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Parenthetical) (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Restricted cash-long-term	$ 10,000
Maximum [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents maturity term	3 months	3 months

Fair Value Measurements - Additional Information (Detail) - USD ($)	Mar. 07, 2017	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Transfer between level 1 and level 2 assets		$ 0	$ 0	$ 0
Guarantee liabilities in other current liabilities		$ 0	$ 1,200,000
Term Loan Agreement [Member] \| Capital Royalty Warrant [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Warrants life	10 years
Warrants issue to purchase common stock	193,788
Warrants exercise price	$ 23.50
Capital royalty warrant value	$ 3,300,000

Term Loan Agreement - Additional Information (Detail) - USD ($)		1 Months Ended		3 Months Ended	9 Months Ended		12 Months Ended		24 Months Ended
	Mar. 07, 2017	Dec. 31, 2016	Jan. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Oct. 01, 2015	Sep. 30, 2015
Debt Instrument [Line Items]
Loan outstanding		$ 81,080,000					$ 81,080,000
Interest rate											11.50%
Interest payable as cash										9.50%
Compounded interest payable										2.00%
Additional amount borrowed				$ 200,000,000	$ 1,236,000	$ 675,000	927,000	$ 153,000	$ 2,300,000
Minimum annual revenues attainable in 2017		80,000,000			80,000,000		80,000,000		80,000,000
Minimum annual revenues attainable after 2017		$ 95,000,000			95,000,000		$ 95,000,000		95,000,000
Present value of the future cash flows		10.00%					10.00%
Minimum annual revenues attained in 2016		$ 65,000,000					$ 65,000,000
Term Loan Agreement [Member]
Debt Instrument [Line Items]
Loan outstanding		$ 81,100,000		30,200,000	$ 82,300,000		$ 81,100,000	30,200,000	$ 82,300,000
Interest rate		11.50%			11.50%		11.50%		11.50%
Interest payable as cash		9.50%			9.50%		9.50%		9.50%
Compounded interest payable		2.00%			2.00%		2.00%		2.00%
Interest-only payments description					Under the Term Loan Agreement, interest is payable at the Company’s option, (i) in cash at a rate of 11.5% per annum, or (ii) at a rate of 9.5% of the 11.5% per annum in cash and 2.0% of the 11.5% per annum (the “PIK Loan”) to be added to the principal of the loan and subject to accruing interest. Interest-only payments are due quarterly on March 31, June 30, September 30 and December 31 of each year of the interest-only payment period, which ends on December 31, 2019.		The other principal terms of the Term Loan Agreement were not amended by the Third Amendment. Accordingly, interest continues to be payable, at the Company’s option, (i) in cash at a rate of 11.5% per annum, or (ii) at a rate of 9.5% of the 11.5% per annum in cash and 2.0% of the 11.5% per annum (the “PIK Loan”) to be added to the principal of the loan and subject to accruing interest. Interest-only payments continue to be due quarterly on March 31, June 30, September 30 and December 31 of each year of the interest-only payment period, which ends on December 31, 2019.
Maturity date for interest-only payment					Dec. 31, 2019		Dec. 31, 2019
Maturity date for principal balance					Mar. 31, 2020		Mar. 31, 2020
Percentage of financing fee	5.00%
Restricted cash balance	$ 10,000,000	$ 2,000,000		$ 2,000,000			$ 2,000,000	$ 2,000,000
Prepayment fee percentage							1.00%
Third Amendment [Member]
Debt Instrument [Line Items]
Percentage of financing fee					3.00%		3.00%
Line of credit facility amount borrowed		35,000,000	$ 15,000,000		$ 50,000,000
Line of credit facility additional borrowing capacity			$ 50,000,000
Third Amendment [Member] \| Other Long Term Liabilities And As Contra-Debt In Notes Payable-Long Term [Member]
Debt Instrument [Line Items]
Accrued back end financing fee		1,500,000			$ 4,100,000		$ 1,500,000		$ 4,100,000
Fourth Amendment [Member]
Debt Instrument [Line Items]
Restricted cash balance	$ 10,000,000	$ 2,000,000					$ 2,000,000
Equity finance completion last date	Jan. 15, 2018
Present value of the future cash flows					10.00%				10.00%
Warrants life	10 years
Warrants issue to purchase common stock	1,937,890
Warrants exercise price	$ 2.35
Fourth Amendment [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Gross proceeds from sale of equity securities on event of default occurred due to going concern qualification	$ 30,000,000

Stockholders' Equity - Additional Information (Detail) - USD ($)				1 Months Ended		3 Months Ended				9 Months Ended		12 Months Ended
	Jan. 01, 2017	Jan. 01, 2016	Oct. 31, 2013	Jul. 31, 2017	Mar. 31, 2015	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares offered for public offering					603,750
Gross proceeds from secondary public offering								$ 23,100,000	$ 64,900,000
Common stock shares issued										24,408		14,897	24,355
Stock-based compensation expenses										$ 10,502,000	$ 8,733,000	$ 11,660,000	$ 13,096,000	$ 14,995,000
Total stock-based compensation expense capitalized as part of cost of inventory										$ 300,000		$ 200,000	$ 100,000
Common stock reserved for future issuance						1,265,000				1,265,000		984,000
Options outstanding												822,838	574,900	501,106
Unamortized compensation expense												$ 14,000,000
Share-based compensation expense remaining vesting term												1 year 10 months 25 days
Expected dividend yield												0.00%
2006 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance												268,560
2013 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance			480,900									56,228
Increase in common stock reserve for issuance	124,382	121,018
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares issued												15,000	24,000	14,000
Secondary Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares offered for public offering								1,850,000	603,750
Shares offering price per share					$ 115.00			$ 12.50	$ 115.00
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase of common stock under ESPP										38,929		69,502
Offering Period										2 years		2 years
Purchase Period										four six-month		four six-month
Stock-based compensation expenses							$ 2,400,000
Increase in common stock reserve for issuance	31,095	30,254
Issuance of common stock available for grant												55,600
Number of shares available for grant												7,846
Common stock reserved for issuance description												The number of shares of common stock reserved for issuance increases on January 1 of each calendar year, from January 1, 2014 through January 1, 2023, by the lesser of (a) one percent (1%) of the number of shares issued and outstanding on the immediately preceding December 31, or (b) such lesser number of shares as determined by the Administrator.
Maximum percentage that employee can contribute for purchase of common stock												15.00%
Expected dividend yield											0.00%	0.00%	0.00%
ESPP [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of common stock reserve for issuance to be increased			1.00%
At The Market (ATM) Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Gross proceeds from secondary public offering						$ 4,300,000
At The Market (ATM) Program [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock, gross				$ 15,000,000
At The Market (ATM) Program [Member] \| Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares offered for public offering						464,108
At The Market (ATM) Program [Member] \| Common Stock [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares offering price per share						$ 10.54				$ 10.54
At The Market (ATM) Program [Member] \| Common Stock [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares offering price per share						$ 5.64				$ 5.64
Selling, general & administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expenses										$ 8,423,000	$ 6,992,000	$ 9,360,000	$ 10,517,000	$ 11,886,000
Non-employees [Member] \| Selling, general & administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expenses												$ 0.0	$ 35,000.0	$ 300,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of remaining stock												3 years
Employee Stock Option [Member] \| 2006 Stock Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options												10 years
Employee Stock Option [Member] \| 2013 Stock Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options												10 years
First Anniversary of Vesting Date [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vested percentage												25.00%
Date of Offering [Member] \| ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock on date of purchase												85.00%
Date of Purchase [Member] \| ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock on date of purchase												85.00%
Scenario, Previously Reported [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares issued												14,876
Scenario, Previously Reported [Member] \| ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase of common stock under ESPP												69,233	30,218

Stockholders' Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Detail) - shares shares in Thousands	Sep. 30, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	1,265	984
Common stock warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	293	99
Shares underlying outstanding stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	933	822
Shares authorized for future equity award grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	39	56
Shares authorized for issuance as ESPP awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance		7

Stockholders' Equity - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model (Detail) - $ / shares	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield			0.00%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (per share)	$ 5.10	$ 37.80	$ 24.30	$ 71.50	$ 142.90
Risk-free interest rate	1.90%	1.40%	1.70%	1.70%	1.80%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%	0.00%
Expected volatility	60.00%	55.50%	57.50%	64.70%	76.30%
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	5 years 9 months 18 days	6 years	5 years 10 months 25 days
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (per share)		$ 26.90	$ 17.80	$ 45.50
Risk-free interest rate		0.60%	0.70%	0.50%
Expected dividend yield		0.00%	0.00%	0.00%
Expected volatility		56.90%	62.70%	61.20%
Expected term (in years)		1 year 3 months 18 days	1 year 3 months 19 days	1 year 3 months 19 days

Stockholders' Equity - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model (Parenthetical) (Detail) - shares	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants made during period		316,671	117,557
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants made during period	0

Stockholders' Equity - Summary for Allocation of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 10,502	$ 8,733	$ 11,660	$ 13,096	$ 14,995
Cost of sales [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	1,022	776	1,016	1,162	1,317
Selling, general & administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	8,423	6,992	9,360	10,517	11,886
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 1,057	$ 965	$ 1,284	$ 1,417	$ 1,792

Commitments and Contingencies - Additional Information (Detail)		9 Months Ended	12 Months Ended
	Jun. 30, 2016 Lease	Sep. 30, 2017 LegalMatter	Dec. 31, 2016 USD ($) LegalMatter	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 01, 2016 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Number of legal proceedings, regulatory encounters or other matters \| LegalMatter		0	0
Noncancelable Operating Lease Agreement Amended Due on May 2019 [Member]
Commitments And Contingencies Disclosure [Abstract]
Amended lease expiration period			2022-05
Tenant improvement allowances received under operating lease				$ 900,000	$ 1,600,000
Unsecured standby letter of credit			$ 500,000
Lease agreement expiration period			Jul. 14, 2019
Barnes Canyon Lease Due on November 2023 [Member]
Commitments And Contingencies Disclosure [Abstract]
Lease agreement expiration period	2023-11
Lease term description			The Barnes Canyon Lease is scheduled to expire in November 2023. The Company will also have a one-time option to extend the term of the lease for a period of not less than 36 months and not greater than 60 months, by delivering notice to the landlord at least nine months and not more than 12 months prior to the expiration of the lease.
Number of option to extend lease term \| Lease	1
Interest accrual rate on amounts utilized from tenant improvement allowance			8.00%
Non structural improvements costs			$ 1,000,000
Reimbursement from landlord			0
TI Rent 2016						$ 0
Tl Rent 2017						500,000
Tl Rent 2018						700,000
Tl Rent 2019						700,000
Tl Rent 2020						700,000
Tl Rent 2021						700,000
Tl Rent 2022 and thereafter						$ 1,300,000
Barnes Canyon Lease Due on November 2023 [Member] \| Other Current Assets [Member]
Commitments And Contingencies Disclosure [Abstract]
Receivables			700,000
Barnes Canyon Lease Due on November 2023 [Member] \| Minimum [Member]
Commitments And Contingencies Disclosure [Abstract]
Period of extended lease term	36 months
Notice period for extend lease term to landlord	9 months
Barnes Canyon Lease Due on November 2023 [Member] \| Maximum [Member]
Commitments And Contingencies Disclosure [Abstract]
Tenant improvement allowances received under operating lease			3,400,000
Period of extended lease term	60 months
Notice period for extend lease term to landlord	12 months
Existing Operating Lease and Barnes Canyon Lease [Member]
Commitments And Contingencies Disclosure [Abstract]
Deferred rent arising from rent escalations and lease incentives			3,700,000	3,700,000
Rent expense			$ 3,100,000	$ 2,600,000	$ 2,100,000

Subsequent Event - Additional Information (Detail)				1 Months Ended	3 Months Ended
Subsequent Event - Additional Information (Detail)	Oct. 17, 2017 USD ($) $ / shares shares	Oct. 09, 2017 shares	Mar. 07, 2017 USD ($) $ / shares shares	Mar. 31, 2015 $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Mar. 31, 2015 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares
Subsequent Event [Line Items]
Number of authorized shares of common stock remains							100,000,000	100,000,000	100,000,000
Shares offered for public offering				603,750
Gross proceeds from secondary public offering \| $					$ 23,100,000	$ 64,900,000
Aggregate principal amount of borrowings outstanding, including total PIK Loans issued \| $								$ 81,080,000
Secondary Public Offering [Member]
Subsequent Event [Line Items]
Shares offered for public offering					1,850,000	603,750
Shares offering price per share \| $ / shares				$ 115.00	$ 12.50	$ 115.00
Subsequent Event [Member]
Subsequent Event [Line Items]
Reverse stock split of company's issued and outstanding shares of common stock description		1-for-10 reverse stock split
Reverse stock split, conversion ratio		0.1
Number of authorized shares of common stock remains		100,000,000
Gross proceeds from secondary public offering \| $	$ 16,200,000
Subsequent Event [Member] \| Secondary Public Offering [Member]
Subsequent Event [Line Items]
Shares offered for public offering	4,630,000
Shares offering price per share \| $ / shares	$ 3.50
Public offering issuance date	Oct. 17, 2017
Subsequent Event [Member] \| Series A warrants [Member] \| Secondary Public Offering [Member]
Subsequent Event [Line Items]
Warrants issue to purchase common stock	4,630,000
Warrants exercise price \| $ / shares	$ 3.50
Public offering period	5 years
Subsequent Event [Member] \| Series B warrants [Member] \| Secondary Public Offering [Member]
Subsequent Event [Line Items]
Warrants issue to purchase common stock	4,630,000
Warrants exercise price \| $ / shares	$ 3.50
Public offering period	6 months
Fourth Amendment [Member]
Subsequent Event [Line Items]
Warrants issue to purchase common stock			1,937,890
Warrants exercise price \| $ / shares			$ 2.35
Equity finance completion last date			Jan. 15, 2018
Restricted cash balance \| $			$ 10,000,000					2,000,000
Fourth Amendment [Member] \| Minimum [Member]
Subsequent Event [Line Items]
Gross proceeds from sale of equity securities on event of default occurred due to going concern qualification \| $			30,000,000
Term Loan Agreement [Member]
Subsequent Event [Line Items]
Restricted cash balance \| $			$ 10,000,000					2,000,000	$ 2,000,000
Aggregate principal amount of borrowings outstanding, including total PIK Loans issued \| $							$ 82,300,000	$ 81,100,000	$ 30,200,000
Percentage of financing fee			5.00%

Summary of Significant Accounting Policies - Summary of Customers Accounted for 10% or More (Detail) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts Receivable [Member] \| Byram Healthcare [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	14.70%	21.80%
Accounts Receivable [Member] \| Edgepark Medical Supplies Inc [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	15.20%	16.40%
Sales Revenue Net [Member] \| Byram Healthcare [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	14.00%	17.20%	10.90%
Sales Revenue Net [Member] \| Edgepark Medical Supplies Inc [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	18.70%	17.80%	16.00%
Sales Revenue Net [Member] \| Solara Medical Supplies, Inc. [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	10.70%
Sales Revenue Net [Member] \| CCS Medical [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more			11.60%

Financial Statement Information - Summary of Accounts receivable (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Receivable Net [Abstract]
Accounts receivable		$ 12,112	$ 14,583
Less allowance for doubtful accounts, and product returns		(940)	(528)
Total	$ 10,582	$ 11,172	$ 14,055

Financial Statement Information - Reconciliation of Change in Estimated Allowance for Doubtful Accounts, and Product Returns (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts
Beginning Balance	$ 735	$ 221	$ 221	$ 253	$ 218
Provision for doubtful accounts and return reserves	$ 664	$ 666	632	70	188
Write-offs and adjustments, net of recoveries			(118)	(102)	(153)
Ending Balance			$ 735	$ 221	$ 253

Financial Statement Information - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 37,665	$ 31,071
Less accumulated depreciation and amortization		(19,256)	(15,545)
Total property and equipment, net	$ 20,286	18,409	15,526
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross		8,851	7,781
Computer equipment and software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross		7,844	6,599
Office furniture and equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross		4,185	3,898
Manufacturing and scientific equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross		$ 16,785	$ 12,793

Financial Statement Information - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Balance Sheet Components [Abstract]
Depreciation and amortization expense related to property and equipment	$ 5.2	$ 4.5	$ 4.1
Amortization expense related to intangible assets	0.3	$ 0.3	$ 0.3
Estimated annual amortization	$ 0.3

Financial Statement Information - Summary of Capitalized Patents (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017
Indefinite Lived Intangible Assets By Major Class [Line Items]
Weighted average remaining amortization period (in months)	66 months	78 months
Patents [Member]
Indefinite Lived Intangible Assets By Major Class [Line Items]
Gross amount	$ 3,247	$ 3,247
Accumulated amortization	(1,463)	(1,137)
Total	$ 1,784	$ 2,110	$ 1,539
Weighted average remaining amortization period (in months)	10 years

Term Loan Agreement - Future Minimum Principal Payments Under Term Loan Agreement (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Long Term Debt By Maturity [Abstract]
2017	$ 0
2018	0
2019	0
2020	81,080
2021	0
Thereafter	0
Total	81,080
Less current portion of notes payable	0
Notes payable, net of current portion	$ 81,080

Stockholders' Equity (Deficit) - Summary of Stock Option Activities for 2006 Plan and 2013 Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options, Outstanding at beginning of period	822,838	574,900	501,106
Options, Granted		316,671	117,557
Options, Exercised	(24,408)	(14,897)	(24,355)
Options, Canceled/forfeited/expired		(53,857)	(19,408)
Options, Outstanding at end of period		822,838	574,900	501,106
Options, Vested and expected to vest at December 31, 2016		812,862
Options, Exercisable at December 31, 2016		423,810
Weighted-Average Exercise Price Per Share, Outstanding at beginning of period	$ 84.05	$ 107.22	$ 102.04
Weighted-Average Exercise Price Per Share, Granted		45.75	120.06
Weighted-Average Exercise Price Per Share, Exercised		11.49	13.82
Weighted-Average Exercise Price Per Share, Canceled/forfeited/expired		126.19	168.63
Weighted-Average Exercise Price Per Share, Outstanding at end of period		$ 84.05	$ 107.22	$ 102.04
Aggregate Intrinsic Value, Outstanding at beginning period	$ 1,593	$ 19,158	$ 23,534
Weighted-Average Exercise Price Per Share, Vested and expected to vest at December 31, 2016		$ 84.24
Aggregate Intrinsic Value, Exercised		$ 1,049	2,540
Weighted-Average Exercise Price Per Share, Exercisable at December 31, 2016		$ 98.61
Aggregate Intrinsic Value, Outstanding at end of period		$ 1,593	$ 19,158	$ 23,534
Weighted-Average Remaining Contractual Life, Outstanding		7 years 11 months 1 day	7 years 11 months 26 days	8 years 7 months 13 days
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2016		$ 1,592
Weighted-Average Remaining Contractual Life, Vested and expected to vest at December 31, 2016		7 years 10 months 28 days
Aggregate Intrinsic Value, Exercisable at December 31, 2016		$ 1,554
Weighted-Average Remaining Contractual Life, Exercisable at December 31, 2016		6 years 9 months 18 days
Scenario, Previously Reported [Member]
Options, Exercised		(14,876)

Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax benefit at federal statutory rate	$ (28,362)	$ (24,616)	$ (27,065)
State income tax, net of federal benefit	(2,393)	(2,285)	(3,912)
Research and development credits	(720)	(1,796)	(646)
Uncertain tax position		3,154
Stock-based compensation	1,686	1,904	1,973
Other	456	550	355
Removal of net operating losses and research and development credits		8,344
Change in valuation allowance	29,318	14,755	29,366
Income tax expense (recovery)	$ (15)	$ 10	$ 71

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Deferred tax assets:
Net operating loss (NOL) carryforwards	$ 100,251	$ 79,233	$ 16,000
Research and development tax credits carryforwards	2,543	1,832	$ 2,900
Capitalized research and development expenses	16,673	13,296
Deferred rent	537	168
Accrued compensation	11,332	9,309
Other	5,931	4,104
Total deferred tax assets	137,267	107,942
Less valuation allowance	(137,267)	(107,942)
Net deferred tax assets	$ 0	$ 0

Income Taxes - California NOL Carry Forwards Expiration (Detail) - California [Member] $ in Thousands	Dec. 31, 2016 USD ($)
Operating Loss Carryforwards [Line Items]
2016	$ 624
2017	2,052
Thereafter	$ 167,828

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Accumulated federal NOL carryforwards		$ 283,500
Accumulated state NOL carryforwards		269,700
Research and development tax credits carryforwards	$ 2,900	2,543	$ 1,832
NOL carryforwards from excess tax deductions		$ 1,800
Deferred Tax Assets Tax Credit Carryforwards Research Expiration Year		2028
Deferred tax assets for NOLs	$ 16,000	$ 100,251	79,233
Shares offered for public offering	603,750
Evaluation of tax position, description		The evaluation of uncertainty in a tax position is a two-step process. The first step involves recognition. The Company determines whether it is more likely than not that a tax position will be sustained upon tax examination, including resolution of any related appeals or litigation, based on only the technical merits of the position. The technical merits of a tax position are derived from both statutory and judicial authority (legislation and statutes, legislative intent, regulations, rulings, and case law) and their applicability to the facts and circumstances of the tax position. If a tax position does not meet the more-likely-than-not recognition threshold, the benefit of that position is not recognized in the financial statements. The second step is measurement. A tax position that meets the more-likely-than-not recognition threshold is measured to determine the amount of benefit to recognize in the financial statements. The tax position is measured as the largest amount of benefit that is greater than 50% likely of being realized upon ultimate resolution with a taxing authority.
Unrecognized tax benefits		$ 5,900
Accrual interest and penalties		$ 0	$ 0
Minimum [Member]
Income Tax Disclosure [Line Items]
Income tax Realization		50.00%
Federal [Member]
Income Tax Disclosure [Line Items]
Research and development tax credits carryforwards		$ 4,100
Tax credit carryforward, expiration date		2026
California [Member]
Income Tax Disclosure [Line Items]
Research and development tax credits carryforwards		$ 4,600
State and Local [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforward, expiration date		2016

Income Taxes - Schedule of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at the beginning of the year	$ 7,594	$ 3,539	$ 1,912
Increases related to current year positions	580	474	476
Increases (decreases) related to prior year positions	(7)	3,581	1,151
Expiration of unrecognized tax benefits	0	0	0
Gross unrecognized tax benefits at the end of the year	$ 8,167	$ 7,594	$ 3,539

Collaborations - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) $ / IntegratedSystem	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2012 USD ($)	Feb. 29, 2016 USD ($)	Sep. 30, 2015 USD ($)
DexCom Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of development costs				$ 1.0
Additional research and development expense upon FDA approval			$ 1.0
Additional payment upon achievement of milestones						$ 1.0
Commit for incremental marketing activities \| $ / IntegratedSystem	100
Marketing fund commitment amount	$ 0.7	$ 0.4
Marketing funds commitment utilized	0.4	0.0
Marketing fund liability amount	0.7	0.4
JDRF Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development offset cumulative amount		0.5
Aggregate amount of milestone payment achievements		$ 0.7
JDRF Agreement [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development offset cumulative amount	$ 3.0
JDRF Termination Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Repayment of milestone payments received					$ 0.7

Employee-Benefits - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Minimum age of employees for defined contribution plan	18 years
Total liabilities	$ 378	$ 222
Mutual funds held for nonqualified deferred compensation plan participants [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	$ 378	$ 222

Commitments and Contingencies - Schedule of Future Minimum Payments Under Noncancelable Operating Leases (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2017	$ 3,198
2018	3,630
2019	1,899
2020	643
2021	662
Thereafter	1,323
Total	$ 11,355

Selected Quarterly Financial Data (Unaudited) (Detail) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

9 Months Ended

12 Months Ended

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Sep. 30, 2017

Sep. 30, 2016

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Revenue

$ 28,912

$ 12,293

$ 22,985

$ 20,058

$ 29,120

$ 15,716

$ 15,706

$ 12,308

$ 17,889

$ 13,513

$ 10,254

$ 8,066

$ 67,306

$ 55,336

$ 84,248

$ 72,850

$ 49,722

Gross profit

10,065

(1,577)

8,176

6,927

13,458

5,513

4,801

2,808

6,537

4,396

3,448

867

26,626

13,527

23,592

26,580

15,248

Operating expenses

23,411

26,837

25,229

26,166

24,679

24,216

23,472

23,218

24,039

23,403

21,766

21,704

79,987

78,232

101,643

95,584

90,912

Operating loss

(13,346)

(28,414)

(17,053)

(19,239)

(11,221)

(18,703)

(18,671)

(20,410)

(17,502)

(19,007)

(18,318)

(20,837)

(53,361)

(64,705)

(78,051)

(69,004)

(75,664)

Net loss

$ (14,822)

$ (29,815)

$ (18,326)

$ (20,485)

$ (12,093)

$ (19,585)

$ (19,533)

$ (21,208)

$ (18,465)

$ (19,901)

$ (19,197)

$ (21,961)

$ (61,627)

$ (68,624)

$ (83,447)

$ (72,418)

$ (79,524)

Basic and diluted net loss per share

$ (4.80)

^[1]

$ (9.70)

^[1]

$ (6.00)

^[1]

$ (6.80)

^[1]

$ (4.00)

^[1]

$ (6.50)

^[1]

$ (6.50)

^[1]

$ (8.30)

^[1]

$ (7.80)

^[1]

$ (8.50)

^[1]

$ (8.30)

^[1]

$ (9.60)

^[1]

$ (13.79)

^[2]

$ (22.52)

^[2]

$ (27.30)

$ (25.04)

$ (34.17)

[1]	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.
[2]	The issued and outstanding shares of common stock have been restated for all periods presented to reflect the effects of the 1-for-10 reverse stock split, which was effective on October 9, 2017 as described in Note 7.